summer 2001 gems & gemology - gia · pdf filetable with trigons •...

pg. 149

EDITORIAL

REGULAR FEATURES

pg. 115

96

FEATURE ARTICLES

Based on recent visits to the pearl farms of Hanzhou Province, the authorsreport on the latest techniques being used to produce Chinese freshwatercultured pearls.

Shigeru Akamatsu, Li Tajima Zansheng, Thomas M. Moses, and Kenneth ScarrattThe Current Status of Chinese Freshwater Cultured Pearls

95Alice S. KellerThe G&G Twenty Year Index: Two Decades of Evolution

124

A new polishing process is being used to create the appearance of aster-ism in gems that have seldom if ever shown this phenomenon previously.

Shane F. McClure and John I. KoivulaA New Method for Imitating Asterism

114

UV-Vis reflectance spectra and fluorescence characteristics are useful indistinguishing undrilled natural- and treated-color yellow cultured pearlsproduced from the Pinctada maxima mollusk.

Shane Elen

Spectral Reflectance and Fluorescence Characteristics of Natural-Color and Heat-Treated “Golden” South Sea Cultured Pearls

130• “Banded” twinned diamond crystal • Diamonds with unusual inclu-sions • Feldspar with chrome diopside inclusions • Gibbsite dyed to imitate nephrite • Devitrified glass resembling jade • Early Japaneseassembled cultured blister pearls • Dyed black faceted cultured pearls• New imitation: “Shell pearls” with a calcite bead

Gem Trade Lab Notes

163 Gemological Abstracts171 Guidelines for Authors

160 Book Reviews

137 Thank You, Donors138

• Royal Asscher cut • Canadian diamonds • PDAC conference • A diamondtable with trigons • “Burmite” • Cat’s-eye amethyst � Brownish red to orange gems from Afghanistan/Pakistan • Clinohumite from Tanzania• An engraved emerald • Unusual rutilated quartz • Rubies and ruby deposits of eastern Madagascar • Ruby crystal with a mobile bubble• Green sapphire with pyrochlore inclusions • Vortex (Yogo Gulch) sap-phire mine update • “Canary” tourmaline from Malawi • Bismuth-bearingliddicoatite from Nigeria • “Jurassic Bugs” amber imitation • Assembled diamond imitations from Brazil • Enamel-backed quartz as a star sapphireimitation • Goldschmidt conference � Moscow gemological conference• Harvard tourmaline exhibit

Gem News International

pg. 108

pg. 133

VOLUME 37, NO. 2Summer 2001

NOTES AND NEW TECHNIQUES

t has been just over 20 years since Gems & Gemologywas redesigned and the “new” format introduced.

Looking at the dozens of covers of these issues, whichdominate the walls of my office, I think of the incredibleeffort that went into each one—the thousands of hoursthat our authors and staff invested in every issue to dothe research, write and refine the articles, and acquire thebest illustrations. I also think of Harold and Erica VanPelt, who photographed the vast majority of the coverimages, as well as the many individuals who loaned valu-able gemstones and jewelry for them to capture on film.

What am I proudest of? The quality of the informationand the depth of knowledge each issuerepresents. Today, 20 years after thefirst issue of the redesigned G&Gappeared, the articles in that issue—onperidot from Zabargad, cubic zirconia,and the detection of diamond simu-lants—are just as solid and useful asthey were in April 1981. Certainly,since then there have been new peridotlocalities, changes in CZ, and morediamond simulants, but these articlescontinue to serve as a solid base forongoing research on those topics.

In the past two decades, we havepublished over 5,500 pages of timely—and timeless—articles, Lab Notes,Gem News entries, Book Reviews, andGemological Abstracts. This is truly a treasure chest ofinformation. But how do you access it? How do you findwhat you need?

We are pleased to provide a solution: our TwentyYear Index (1981–2000). We have revised and updatedthe subject and author listings from our first 15 years,and added the annual indexes for the last five.

In the course of preparing this Index, we were allstruck by the changes that were necessary since ourfirst index was published in Winter 1981—changes notonly in gemology, but also in geography and technolo-gy, many of them interrelated.

For example, the most significant change to the geopo-litical landscape since the Spring 1981 issue has been thebreakup of the Soviet Union. For our industry, however,this change has been more profound than the simplereplacement of names on a map. With the new socioeco-nomic climate in this region has come an influx of natu-ral gem materials onto the world market—most notablyfrom the release of diamonds that were in the governmentstockpile, but also from renewed mining activity for suchclassic gems as demantoid garnets. There also has been anunprecedented impact on the availability of syntheticgem materials—new synthetic rubies, sapphires, emer-alds, and quartz varieties, to name but a few. Russian high

pressure/high temperature (HPHT) presses are now syn-thesizing diamonds in virtually every color.

In other regions, names that were unknown to most ofus only five years ago are now part of the gemological par-lance—Tunduru in Tanzania, Ilakaka in Madagascar,Ekati in Canada. The availability of these significant newdeposits of sapphires, rubies, and diamonds has shiftedthe balance of supply and demand. At the same time, ithas presented greater challenges to gemologists in identi-fying sources and treatments.

Scientific advances in the U.S. and elsewhere alsohave brought us synthetic moissanite, the first diamond

simulant to match the thermal proper-ties of diamond. Whereas there wasalmost nothing written on diamondtreatments in the 1980s, articles ondiamonds that have been fracturefilled or HPHT processed are promi-nent in the current index. Our firstindex simply referred to “spec-troscopy.” Today, there are entries formore than 10 different types of spec-troscopy. Laser Raman microspec-trometry—which we first reported ononly three years ago—is now used rou-tinely in major gem labs around theworld to identify inclusions and gemmaterials, as well as to recognizeHPHT annealing in diamonds.

For this veteran of two decades of G&G, the AuthorIndex offered a distinct pleasure as I was reminded ofthose who have contributed so much to the journal.“Godfathers” of gemological research such as RobertCrowningshield, Edward Gübelin, Richard T. Liddicoat,and Kurt Nassau were joined by an impressive group ofnew researchers such as Emmanuel Fritsch, Henry Hänni,Bob Kammerling, Bob Kane, John Koivula, ShaneMcClure, Tom Moses, Ken Scarratt, Karl Schmetzer, andJames Shigley, among many others.

We hope that you too will enjoy using the index andfind it a valuable reference tool. Explore the thousandsof entries to learn what you need to know to stayabreast of the rapidly evolving world of gemology.

Alice S. KellerEditor

[email protected]

Note: See the ad on page 159 of this issue to purchase a printedcopy of the Gems & Gemology Twenty Year Index, or access itfree of charge by visiting us online at www.gia.edu/gandg.

EDITORIAL GEMS & GEMOLOGY SUMMER 2001 95

The GG&&GG TTwweennttyy YYeeaarr IInnddeexx:

Two Decades of Evolution

I

THE CURRENT STATUS OF CHINESE

FRESHWATER CULTURED PEARLS

96 CHINESE FRESHWATER CULTURED PEARLS GEMS & GEMOLOGY SUMMER 2001

demand for information, two of the authors (SAand LTZ) visited six FWCP farms and one nucleusmanufacturer in China’s Zhejiang district; theyalso examined hundreds of Chinese FWCPs. Thetrip was made from July 25 to 29, 2000; informa-tion in this article has been confirmed and updat-ed since then based on the second author’smonthly trips to the pearl-farming areas to visithis pearl factory in Zhuji City, as well as to pur-chase freshwater cultured pearls for export. Inaddition, the first author has visited Chinesefreshwater pearl-culturing areas several times dur-ing the past two years. This article reports on thecurrent status of the Chinese freshwater culturedpearl, both the various culturing techniques usedand the cultured pearls themselves, updating (andsuperseding) the pearl-culturing information inScarratt et al. (2000).

By Shigeru Akamatsu, Li Tajima Zansheng,Thomas M. Moses, and Kenneth Scarratt

See end of article for About the Authors information and Acknowledgments.GEMS & GEMOLOGY, Vol. 37, No. 2, pp. 96–113© 2001 Gemological Institute of America

Chinese freshwater cultured pearls (FWCPs) are assuming a growing role at major gem and jewelry fairs, andin the market at large. Yet, it is difficult to obtain hard information on such topics as quantities produced, inwhat qualities, and the culturing techniques used because pearl culturing in China covers such a broad area,with thousands of individual farms, and a variety of culturing techniques are used. This article reports onrecent visits by two of the authors (SA and LTZ) to Chinese pearl farms in Hanzhou Province to investigatethe latest pearl-culturing techniques being used there, both in tissue nucleation and, much less commonly,bead (typically shell but also wax) nucleation. With improved techniques, using younger Hyriopsis Cumingimussels, pearl culturers are producing freshwater cultured pearls in a variety of attractive colors that are larg-er, rounder, and with better luster. Tissue-nucleated FWCPs can be separated from natural and bead-nucle-ated cultured pearls with X-radiography.

he popularity of Chinese freshwater cul-tured pearls (FWCPs) has risen dramaticallyin the world’s markets. The unique charac-

teristics of the Chinese FWCP—in terms of size,shape, and color—have been key to this popularity(figure 1). Chinese FWCPs are available in sizesranging from 2 mm to over 10 mm; in an interest-ing variety of shapes such as round, oval, drop,button, and baroque; and in rich colors such asorange and purple, often with a metallic luster.The vast majority of these Chinese FWCPs arenucleated by mantle tissue only, although somenucleation with spherical beads has taken place(Bosshart et al., 1993; “China producing nucleatedrounds,” 1995; Matlins, 1999; “China starts...,”2000; Scarratt et al., 2000). This makes them dis-tinct from the overwhelming majority of culturedpearls from other localities, which are bead nucle-ated. Despite the growing popularity of ChineseFWCPs, details concerning their history, culturingareas, production figures, culturing techniques,and the characteristics of the pearls themselvesare not widely known. In response to the growing

T

CHINESE FRESHWATER CULTURED PEARLS GEMS & GEMOLOGY SUMMER 2001 97

HISTORYThe culturing of freshwater pearls was widespreadin China by the 13th century. Tiny figures ofBuddha formed of lead were cemented onto thenacreous interior of the shell produced by the fresh-water mussel Cristaria plicata (zhou wen guanbang in Chinese). Over time, the mollusk coatedthe lead figures with nacre, and the blister pearlsthus cultured were used as temple decorations oramulets (Ward, 1985; Webster, 1994). Even now,this culturing technique survives, although theimages are larger and nucleated with wax ratherthan lead (figure 2). Today, images of Buddha, flow-ers, birds, animals, and other forms are molded withwax and inserted into the mussels. A similar tech-nique is used to create the mabé-type hemisphericcomposite cultured blister pearls in white- andblack-lipped pearl oysters, as well as in abalone(Wentzell, 1998).

Freshwater pearl culturing was attempted inJapan around 1910, but success was not achieveduntil 1924, when growers changed from the“Karasu” mussel (C. plicata) to the “Ikecho” mus-sel (Hyriopsis schlegeli). Following this success,commercial freshwater pearl culturing began inJapan in 1928. A bead-nucleating technique wasfirst adopted, but growers eventually recognizedthat tissue nucleation produced better results. In1946, freshwater-pearl farmers switched to tissue

nucleation, creating unique freshwater culturedpearls. Since then, Japanese FWCPs have beenhighly prized as “Biwas” (named after Lake Biwa,

Figure 2. The culturing of freshwater blister pearls waswidespread in China by the 13th century. Tiny figuresof Buddha were cemented onto the inner shell offreshwater mussels (Cristaria plicata), where theywere coated with nacre. The same culturing techniquesurvives today. Instead of tiny lead figures, larger waximages are commonly used to produce a variety offorms, although Buddha (as seen in this 8.3 × 10.8 cmshell) is still popular. Photo by Shigeru Akamatsu.

Figure 1. Chinese fresh-water cultured pearlsoccur in a variety ofattractive shapes andcolors, as well as in sizesover 10 mm. The potato-shaped Chinese FWCPsin the strand on the leftrange from 9.3 × 11.3mm to 10.6 × 12.7 mm.The near-round ChineseFWCPs on the right areapproximately 9–10mm. Photo © Harold &Erica Van Pelt.

where most were grown). Over time, improve-ments in the culturing technique produced morepearls of better quality, and the Japanese freshwa-ter pearl culturing industry flourished. Pearl cul-turing at Lake Kasumigaura began in 1962, and in1980 production reached a peak of 6.3 tons.Production began to decline because of water con-tamination and the high mortality of the mussels(Toyama, 1991). By 1998, production of Japanesefreshwater cultured pearls had dropped to 214 kg,only 3.4% of the peak in 1980 (“Statistics of fish-ery and cultivation,” 2000).

It was in the late 1960s and early 1970s thatChina started full-scale FWCP production, and low-quality irregular-shaped cultured pearls with wrin-kles on their surface (commonly known as “RiceKrispie” pearls) appeared in the market (Hiratsuka,1985; figure 3). According to trade statistics pub-lished by the Japanese Ministry of Finance, in 1971Japan imported only 600 grams of this material.Over the next 13 years, however, these importsincreased dramatically: They reached 7.5 tons in1978, 34 tons in 1983, and over 49 tons in 1984.Most were not consumed by the Japanese market,but instead were exported to Germany,Switzerland, Hong Kong, the Middle East, and theU.S. by Japanese distributors (Chinese FWCPsaccounted for more than half the pearls exportedfrom Japan in 1984). In the late 1980s, however, thedemand for such low-quality pearls quickly dieddown, and the Chinese FWCP almost disappearedfrom the world market.

In the 1990s, however, Chinese FWCPs reap-peared, with their quality remarkably improved(“China starts pearling revolution,” 2000).Culturers had changed the species of mussel fromC. plicata to Hyriopsis cumingi, which is general-ly called the “triangle mussel” (san jiao or sanjiao bang in Chinese) because of its shape (figure4; Fukushima, 1991). The triangle mussel inhabitswide areas along the Chang Jiang (Yangtze) River.Using the new mussel, growers started to culti-vate 3–4 mm pearls with a smooth surface.Although some of these Chinese FWCPs werenear-round, more often the commercial producthad a bulbous oval “potato” shape (again, see fig-ure 1). Over the last decade, quality continued toimprove. Chinese cultivators now produceFWCPs in sizes from 2 mm to over 10 mm, inshapes from extreme baroque to perfect round,and in colors from white to pastel orange and pur-ple, often with a metallic luster.


Figure 4. Chinese pearl farmers greatly improved the qualityof their product in the 1990s by changing the mussel speciesfrom Cristaria plicata to H. Cumingi, the Chinese “triangle”

mussel. With the use of H. Cumingi both as donor of the man-tle tissue and for culturing, they produced larger culturedpearls with a smoother surface, rounder shape, and better

color and luster. In particular, the color and luster of themother-of-pearl in the tissue-donor mussel has a strong influ-ence on the color and luster of the final cultured pearl; notice

the differences among these four mussels, all of which wereused to provide mantle tissue nuclei. Although earlier cultur-ing with H. Cumingi was done using 2–2.5 year old mussels,these one-year old mussels are typical of the age at which H.Cumingi are nucleated today. Photo by Shigeru Akamatsu.

Figure 3. Most of the Chinese FWCPs cultivated withCristaria plicata were of low quality: irregular shaped

with many wrinkles on their surface (hence called “RiceKrispies”; here, 5 × 8 mm to 9 × 14 mm, produced in

1976). These pearls first appeared on the market in thelate 1960s and early 1970s, with 600 grams imported

into Japan in 1971. The quantity increased dramaticallyover the next several years (with Japanese imports of 49

tons in 1984), but the boom had faded by the late 1980s.Photo by Maha Tannous.

CULTURING AREAS ANDPRODUCTION AMOUNTThe culturing region for Chinese FWCPs extends overwide areas along the Chang Jiang (also known as theYangtze) River (figure 5). The provinces of Jiangsu,Zhejiang, Anhui, Fujian, Hunan, and Jiangxi are themain culturing areas, with Jiangsu and Zhejiangaccounting for nearly 70% of the total FWCP produc-tion (He Xiao Fa, pers. comm., August 2000).

It is generally thought that pearls cultured insouthern farms grow faster, coinciding with therapid growth of the mussel. By contrast, pearls cul-tured in northern farms grow more slowly, but theircompact nacre gives them a better luster. For thisreason, some farmers who own both northern andsouthern farms initially cultivate pearls in thesouthern farms to accelerate nacre growth, thenmove the mussels to northern farms one year beforeharvest to improve the luster. In addition, northernfarmers often buy nucleated mussels from southerncultivators. According to several pearl culturers inthe cities of Zhuji and Shaoxing, transferring mus-sels from one farm to another during the pearlgrowth period (which may take up to six years) isnot uncommon in China.

No accurate production figures exist for ChineseFWCPs. Two major culturers, He Xiao Fa ofShanxiahu Pearl Co. Ltd. and Ruan Tiejun of FuyuanPearl Jewelry Co. Ltd., estimate that annual produc-tion is currently about 1,000 tons. Because there areseveral thousand pearl farms, many of which arevery small, it is impossible to give an accuratecount. The farms range from major operations withover one million mussels, to tiny roadside swampsdiverted from rice paddy fields that contain tens ofthousands of mussels (see, e.g., figure 6). The mus-sels are suspended in nets (each typically containingtwo to three mussels; figure 7) from buoys that areoften made of Styrofoam or recycled plastic bottles.

RECENT DEVELOPMENTS INTISSUE NUCLEATIONFrom observations made during our frequent visits,and from conversations with several leading pearlfarmers, we confirmed that the vast majority of fresh-water cultured pearls produced in China today are, asstated in Scarratt et al. (2000), mantle-tissue nucleat-ed. As the recent improvement in quality demon-strates, the growth techniques used to create theChinese product have changed. Some of the changescan be counted as major technical improvements.

New Mussel Species Used for Culturing. As notedabove and in Scarratt et al. (2000), Chinese pearlcultivators have changed from the C. plicata mus-sel to the H. cumingi (”triangle”) mussel. H.cumingi is a large bivalve of the same genus as theH. schlegeli used for pearl cultivation in Japan’sLake Biwa. Triangle mussels can produce attrac-tive FWCPs with a smooth surface. With the intro-duction of hatchery techniques to propagate the H.Cumingi, mass production of mussels has becomepossible and enormous amounts are now used forpearl culturing.


Figure 5. Freshwater pearl culturing areas extendwidely along the Chang Jiang (Yangtze) River,including the provinces of Jiangsu, Zhejiang, Anhui,Fujian, Hunan, and Jiangxi. Mussels that have beentissue nucleated are not always cultivated in a singlefarm for the entire culturing process. Often they aretransferred to other farms in different provinces,where cultivation continues.

A Longer Culturing Period. In the past, it was com-mon for growers to perform tissue nucleation ontwo-and-a-half-year-old mussels, cultivate them fortwo to three years thereafter, and harvest 4–7 mmpearls (see, e.g., Jobbins and Scarratt, 1990). In recentyears, however, some growers have been operatingon significantly younger mussels, approximatelyone to one-and-a-half years old (figure 8, right), andcultivating them for four to six years. By extendingthe period between insertion of the tissue nucleiand the harvest, they have succeeded in producingcommercial quantities of FWCPs larger than 8 mm.A one-year-old mussel has a small shell, one valveof which weighs only 10 grams (average dimen-sions: 7.2 × 4.3 cm) at the time of nucleation. Thatsame valve will attain a shell weight at harvest after

five years of 260 grams (up to 16.4 × 10.5 cm), morethan 25 times its starting weight (figure 8, left). Thepearls grow as the mussels grow, but the rate ofgrowth is not always proportional.

Even though the cultivation period from nucle-ation to harvest is the same for any given mussel,the growth rate of the many pearls nucleated in thatmussel is not the same. Consequently, FWCPs ofvarious sizes are harvested from a single mussel (fig-ure 9). Table 1 lists the different sizes of FWCPsremoved from a sample harvest of four mussels thatwere cultivated for 4.5 years in a farm in Shaoxing.


Figure 6. In China, the number of farms culturing freshwater pearls is too large to be counted accurately. Theyvary in size from large lakes (left) to small farms converted from rice paddy fields (right). Note the soil piledaround the paddy field to keep the water deep enough (1.5 m) for pearl culturing. Photos by Shigeru Akamatsu(left) and Li Tajima Zansheng (right).

Figure 7. During pearl cultivation, two to threemussels typically are put in a net and suspended inthe water from Styrofoam buoys or recycled plasticbottles. Photo by Shigeru Akamatsu.

Figure 8. A one-year-old “triangle” mussel at thetime of tissue nucleation is very small (right)—anaverage of 7.2 × 4.3 cm, with an approximate shellweight (one valve) of 10 grams. A six-year-old H.cumingi mussel at the time of harvest (left) afterfive years of cultivation is very large—up to 16.4 ×10.5 cm, with a single valve now 260 grams inweight. Photo by Li Tajima Zansheng.

These results also indicate that cultivation periodsof 4.5 years can produce FWCP sizes of over 9 mm.Note that these mussels were older and larger whenthe nuclei were inserted than is currently practiced

Improvement in the Mantle Tissue Nucleus. In ear-lier freshwater pearl culturing, a common techniquewas to cut a 2 × 2 mm piece of tissue from the man-tle of a 2.5-year-old mussel, fold it, and then insert itinto a pocket made in the mantle lobe of a host mus-sel (Jobbins and Scarratt, 1990). Because this piece oftissue was too thick to be worked into a roundshape, most of the FWCPs produced had shapes suchas rice, oval, and baroque. Recently, pearl farmershave changed the nature of the mantle-tissue nuclei.Instead of taking the tissue from a 2.5-year-old mus-sel, growers now use a one-year-old (H. cumingi)mussel for this part of the procedure. When a pieceof tissue is removed from such a young mussel, it isthin enough to be rolled into a round ball. So the cul-turer now cuts a larger (but thinner) 4 × 4 mm pieceof mantle tissue (figure 10), and makes it as round aspossible by rolling it before nucleation (figure 11).

Improvements in the Nucleation Technique. Fromtheir experience, pearl culturers identified that theposterior mantle lobe of the mussel, where the moth-er-of-pearl has the desired color and luster, is the keylocation to produce a better-quality pearl with finecolor and luster (again, see figure 4). So they started tocut pieces of tissue from the posterior part of the sac-rificed “donor” mussel and then placed them intopockets in the same posterior mantle lobes of thehost mussel (figure 12). With this new technique,

pearl culturers are improving the color and luster oftheir FWCPs. Figure 13, taken in April 2001, shows agroup of technicians performing different stages ofthe pearl nucleation technique at this pearl-process-ing operation in a suburb of Zhuji City.

Another improvement is the reduction in thenumber of tissue pieces used to nucleate a singlemussel. In the past, when cultivators used relative-ly large, 2.5-year-old mussels to begin the process,about 20 pieces usually were inserted in each man-tle lobe of the bivalve—for a total of about 40pieces in a single mussel (Farn, 1986; Scarratt etal., 2000). Now, some growers typically insert 14or fewer pieces of tissue in each mantle lobe of aone-year-old mussel—for a total of 28 or fewer ineach mussel (figure 14).


Figure 9. All the Chinese FWCPs in this photo weretissue nucleated and harvested from both valves ofone mussel after 4.5 years. Even though the culturingconditions were the same, the resulting FWCPsrange from 5 to 9 mm. Photo by Shigeru Akamatsu.

TABLE 1. Freshwater cultured pearls produced from four mussels harvested inShaoxing after cultivation for 4.5 years.a

Mussel 1 Mussel 2 Mussel 3 Mussel 4

Size (mm) No. of % of No. of % of No. of % of No. of % of FWCPs total FWCPs total FWCPs total FWCPs total

4 0 0 1 2.9 2 3.8 0 05 4 9.5 5 14.3 20 37.7 1 3.06 12 28.6 13 37.1 21 39.6 8 24.27 13 31.0 12 34.3 6 11.3 16 48.58 10 23.8 3 8.6 3 5.7 8 24.29 3 7.1 1 2.9 1 1.9 0 0

Total 42 35 53 33

aNote that these mussels were older when they were nucleated, and had more nuclei inserted, than pearl farmersnow prefer.

Movement of Mussels Among Different Farms. Weobserved not only that culturers sold the live, oper-ated mussels for further growth in the farm ofanother producer, but also that as they recognizeddeficiencies or changes in the environments oftheir farms, they often moved their own mussels tomore suitable farms. Culturers also have found thatthe change in farms places the mussels under atype of “stress” that activates their respiration sothat they produce more carbon dioxide (Koji Wada,pers. comm., 2001). The carbon dioxide converts tocarbonate ions that combine with the calcium ionsto form more calcium carbonate crystals. Thisimproves the nacre growth, thus promoting goodluster and color, as well as larger pearls.

FWCP CULTIVATION WITH SOLID NUCLEIAlthough, as noted above, the vast majority ofChinese FWCPs currently are tissue nucleated, vari-ous methods to culture the FWCP by inserting asolid bead nucleus are being practiced (“China pro-ducing nucleated rounds,” 1995). Use of a beadnucleus is still being done on a limited scale only,because of the higher cost of production and theinferior quality of the pearls produced. According to


Figure 12. The operator places a one-year-old musselon a fixing stand and opens the shell with care, mak-ing pockets in the posterior mantle lobes and insertingrolled pieces of mantle into them, as illustrated in thediagram (inset). A skilled technician can operate on120 mussels a day. Photo by Shigeru Akamatsu.

Figure 10. Using a knife, the technician cuts apiece approximately 4 × 4 mm from a strip of tissuethat was removed from the mantle lobe of an H.Cumingi mussel of about the same age as the one-year-old H. Cumingi into which it will be inserted.Photo by Shigeru Akamatsu.

Figure 11. Just before nucleation, the thin pieces ofmantle tissue are rolled as round as possible.Because the piece of mantle tissue is so thin, it canbe rolled into a round ball more efficiently than thethicker (2 × 2 mm) pieces of tissue that were typi-cally used in the past. Photo by Shigeru Akamatsu.

Chinese pearl-culturing textbooks (Li and Zhang,1997; Li, 1997), the main methods used to beadnucleate Chinese FWCPs are as described below.

Insertion of Bead Nuclei into Mantle Pockets. TheChinese textbooks cited above report that pocketsare cut into the mantle lobes of large and healthyfive- to eight-year-old H. cumingi mussels, and thesame round shell beads typically used for saltwaterpearl culturing are inserted together with pieces oftissue cut from the mantle of another H. Cumingimussel (figure 15). The implantations typicallytake place from March through May and fromSeptember through November, but the latter periodyields better results.

The spherical bead nucleus varies from less than2 mm to over 8 mm, while the piece of mantle tis-sue usually is smaller than 2 × 2 mm. For the bestproduct, the size of the piece of tissue must be con-sistent with the size of the bead nucleus. When thepiece of tissue is too large relative to the bead,pearls with a poor shape, wrinkles, or blemishescommonly result. Conversely, according to thetextbooks, if the piece of tissue is too small, it caneasily separate from the nucleus, resulting in a tis-sue-nucleated FWCP and the possible expulsion ofthe bead. The solid nucleus normally is cut fromthe interior of a Chinese or American freshwater

mussel (see “The Bead Nucleus” section below),but paraffin wax also is used by some pearl farmers.

When paraffin is used, typically spherical waxbeads about 2 mm in diameter are inserted into amussel (H. cumingi) to produce 5–7 mm FWCPs (fig-ure 16). If these cultured pearls are heated whendrilled, the liquefied paraffin will ooze out of thedrill hole, leaving a small hollow core. Solvents suchas bleaching reagents can easily enter such hollowFWCPs, facilitating this processing. Thus, the use ofparaffin nuclei has a possible three-fold purpose: (1)produce round pearls, (2) lower the cost of the nucle-us, and (3) facilitate processing after harvest.

Modified Direct (or “D”) Operation. This method issimilar to that used in South Sea and Tahitian pearlcultivation, with the exception that (as noted above)


Figure 13. Several technicians are simultaneouslypreparing the mantle tissue and inserting thepieces into the young H. Cumingi mussels at thispearl-processing operation in a suburb of ZhujiCity. Photo by Li Tajima Zansheng. Figure 14. Shown here is a one-year-old mussel just

after a tissue-nucleating operation in July 2000. Inaccordance with the current practice of this cultivator,14 pieces of mantle tissue were inserted into the poste-rior part of each of the two mantle lobes (to produce atotal of 28 pearls). In recent years, fewer pieces ofmantle tissue have been used to facilitate the produc-tion of larger FWCPs. Photo by Shigeru Akamatsu.

the bead nuclei are inserted into the mantle of thehost mussel for (freshwater) Chinese cultured pearls,whereas for (saltwater) South Sea and Tahitian cul-tured pearls the bead is inserted into the gonad. Aftera mussel nucleated by the usual tissue-insertionoperation is harvested, the technicians carefully cutout the FWCPs and then, rather than discarding theanimal, they insert a shell bead nucleus into eachpearl sac where a tissue-nucleated FWCP had grown(figure 17). With this procedure, there is no need toinsert a piece of tissue with the bead nucleus becausethe pearl sac is already formed. Usually bead nuclei5–6 mm in diameter are inserted into pearl sacsformed in the mantle lobes, and culturing continuesfor one to two years. Because at the time of the firstharvest the mussel is already a little old, the colorand luster of the bead-nucleated pearl produced bythis second procedure typically will not be as good asthat of the original tissue-nucleated FWCP (Li andZhang, 1997; Li, 1997). Nevertheless, some attractivepearls have been cultured by this process (figure 18).


Figure 16. Recently, small paraffin balls also havebeen used as bead nuclei. When the cultured pearlis heated during drilling, the wax can melt out,leaving a small void that makes treatment easier.The cultured pearls shown here are 5–7 mm indiameter. Photo by Maha Tannous.

Cut a tip of mantle lobe

Make a pocket with a needle

Insert a nucleus into the pocket

Push the nucleusinto proper positionin the pocket

Place a small piece of mantle tissue into the pocket with the nucleus

Operation finished

1

2

3

4

5

6

BEAD NUCLEUS INSERTIONBEAD NUCLEUS INSERTION

Figure 15. Bead nucleation of Chinese FWCPs usuallyinvolves insertion of the bead nucleus together with apiece of mantle tissue into a pocket made in the man-tle lobe. Most commonly the beads are fashioned fromthe shell of a Chinese or American freshwater mussel.Adapted from Li (1997).

Insertion of the Bead into the Mussel’s Body. Tomake FWCPs over 10 mm, relatively large nuclei (8to 12 mm in diameter) are inserted together withpieces of tissue into the body of the H. cumingi mus-sel—as distinct from the mantle lobes in the bead-nucleation procedure described earlier—usuallyunder the liver and/or the heart (figure 19). This is thesame technique currently used to produce Kasumigafreshwater cultured pearls in Japan (Hänni, 2000).

The Bead Nucleus. Japan was once the only countrythat manufactured shell bead nuclei for pearl cultur-ing, but now China also produces and supplies shellbeads to Chinese pearl culturers. By visiting one ofthe nucleus manufacturers—Theng Xuan An ofPenfei Youhezenzhu Co., Zhuji—two of the authors(SA and LTZ) learned about some of the Chinesenuclei. In China today, bead nuclei for saltwater aswell as freshwater pearl culturing are fashioned


Figure 18. These Chinese FWCPs were bead nucle-ated by a modified “D” operation. The cross-sec-tion is 8 mm in diameter; the whole samples rangefrom 7.5 mm in diameter to 9 × 10 mm. Photo byMaha Tannous.

Place a curved holder on the inner surface of the mantle next to the pearl sac

Cut open the tip of the pearl sac with a bladed needle

Remove the cultured pearl from the pearl sac by pushing with the curved holder

Insert a bead nucleus into the new vacant pearl sac and continue cultivation;there is no need for a piece of mantle to accompany the bead because the pearl sac is already formed

A bead-nucleated pearl is produced

1

2

3

4

5

BEAD NUCLEATION by DIRECT OPERATIONBEAD NUCLEATION by DIRECT OPERATION

Figure 17. Some Chinese pearl farmers use a direct (or“D”) operation modified from a similar process used toproduce saltwater cultured pearls in the South Seasand Tahiti. After removing the tissue-nucleated FWCP,the technician inserts a shell bead nucleus into theexisting pearl sac to grow another pearl. Mantle tissueis not needed in this case because the pearl sac isalready formed. Adapted from Li (1997).

from both Chinese and American freshwater mus-sel shells; Mr. Theng’s factory uses the same trian-gle mussel in which the freshwater pearls are cul-tured as the shell for beads, too. We are aware thatshells cut from other mussels, such as Lamprotulaleai, are also used for bead cultivation in China (D.Fiske, pers. comm., 2001). To fashion the nuclei(typically 5–7 mm in diameter), PenfeiYouhezenzhu Co. uses machines imported from

Japan and the same procedure as is used in Japan.These beads are also exported to other pearl-produc-ing countries such as Japan and Tahiti.

Reports in the trade literature have suggestedthat some bead nuclei are made by grinding tissue-nucleated FWCPs into a round shape (Matlins,1999; Roskin, 2000). In our visits with a Chinesenucleus manufacturer and numerous pearl cultur-ers, we found no evidence of the commercial man-ufacture of such nuclei. Recently, one of theauthors (SA) asked a Japanese nucleus manufactur-er to fashion such nuclei from tissue-nucleated 10mm “potato” FWCPs to examine the appearanceand potential effectiveness of such a bead. By theusual shell-bead manufacturing procedure, theFWCPs were ground to round. The result was notsatisfactory, because the nacre peeled unevenlyduring grinding to produce a poor sphere.

CHARACTERISTICS OF CHINESE FWCPsMaterials and Methods. As described in the intro-duction, Chinese FWCPs are distinctive in terms ofsize, shape, color, and luster. Their internal struc-ture also is unique. To study these characteristics,two of the authors (SA and LTZ) examined approxi-mately 500 sample Chinese FWCPs—ranging from2 mm to 13 mm (figure 20)—that were selectedfrom the stock (about 100 kg) of Stream Co. Theseare representative in color and luster of the better-quality cultured pearls being sold in China at thistime. The stock was harvested from a few Zhujiand Shaoxing pearl farms in July 2000. The buyersat Stream Co. purchased all of these samples as tis-sue-nucleated FWCPs; only a few farms in theseareas culture bead-nucleated FWCPs.

All of the pearls were examined visually by twoof the authors (SA and LTZ). Approximately 50 tis-sue-nucleated FWCPs were cut in half so that wecould examine the internal structure with a loupe.

Structure. Because the vast majority of ChineseFWCPs are tissue nucleated, solid nuclei are notnormally seen. Most of the sawn tissue-nucleatedFWCP sections showed traces of the tissue nucleusat the center, although in some samples they weredifficult to discern (figure 21). For this reason, as dis-cussed in depth in Scarratt et al. (2000), the separa-tion of natural from tissue-nucleated cultured pearlsis best done with X-radiography (see Appendix A).The cross-sections of the more strongly coloredsamples also showed distinct concentric color bands


Figure 20. Commercial round Chinese FWCPs rangefrom 2 mm to over 13 mm. The sizes of tissue-nucle-ated FWCPs are closely related to the culturing peri-od: 2 mm FWCPs such as the one on the far left can

be produced by a culturing period of less than twoyears, but the 13 mm FWCP on the far right typical-ly requires more than six years. Note also the range

of colors and the metallic luster in some of thesesamples. Photo by Li Tajima Zansheng.

Figure 19. To produce FWCPs over 10 mm, somecultivators insert larger (8–12 mm diameter) butfewer (usually one or two) bead nuclei togetherwith pieces of mantle tissue into the body of themussel under the liver and/or the heart. Adaptedfrom Li (1997).

between nacreous layers. These bands seem to berelated to the same mechanism that produces thevarious colors observed in the shell nacre of thehost H. cumingi mussel (figure 22).

Shape. In the past, Chinese FWCPs were typicallyelongated and wrinkled or pitted (again, see figure3). Although most Chinese FWCPs continue tobe oval or other shapes, the improvements in cul-turing techniques described above (e.g., the use ofyounger, thinner pieces of mantle tissue that canbe rolled into a ball) have brought a greater num-ber of round and near-round FWCPs to the mar-ketplace (figure 23).

Today, the most popular shapes are round, near-round, oval, button, drop, semi-baroque, and otherssuch as sticks and crosses. This wide variety ofshapes is characteristic of FWCPs from sourcesaround the world. The group we examined werespecifically selected to be round to near round.

Color. Chinese FWCPs occur in three main hues—white, orange, and purple—all of which were repre-sented in our sample. Combinations of tone andsaturation yield a broad range of color appearances(figure 24) from which very attractive and distinc-

tive jewelry has been fashioned (figure 25). Pearldealers have described some Chinese FWCPs as“wine,” “cognac,” “lavender” (figure 26), “blueber-ry,” and “apricot.” This color range is believed tobe associated with: (1) the color of the mother-of-pearl in the donor mussel from which the piece ofmantle tissue was taken, (2) the environmentalconditions of the culturing farm, and/or (3) the age


Figure 23. The new tissue-nucleation techniquesbeing used in China have led to a greater numberof round freshwater cultured pearls in the market-place. Photo by Shigeru Akamatsu.

Figure 21. The evidence of tissue nucleation inChinese FWCPs can be very subtle. In most ofthese four tissue-nucleated samples, the nucleuscan be seen as a fine line toward the center of thesphere. Because such sawn sections are a highlydestructive means of identifying the type of nucle-us, and even they may not reveal the necessary evi-dence (if, for example, the tissue nucleus is slightlyoff-center), X-radiography is the best method toseparate tissue-nucleated cultured pearls fromtheir natural or bead-nucleated counterparts.During cultivation, growth rings of different colorsform in some FWCPs. Photo by Shigeru Akamatsu.

Figure 22. When the periostracum (the outer layerof the shell) of the triangle mussel H. Cumingi isremoved, the beautiful color and luster of thenacre are revealed. Insertion of mantle tissue takenfrom the posterior of the mussel into the posteriorof the live mussel is the key to producing bettercolor and luster. Photo by Shigeru Akamatsu.

of the host mussel. The first of these probably hasthe greatest effect on the color of an individualFWCP (Li and Zhang, 1997).

Luster. Our sample Chinese FWCPs demonstrated awide range of luster, from dull and chalky to metal-lic. On the basis of on-site investigations and inter-views with several cultivators in Shaoxing, two ofthe authors (SA and LTZ) concluded that the fol-lowing four factors can influence the luster ofChinese FWCPs:

• The nature of the piece of mantle tissue used• The location in the mussel where the tissue

piece is inserted• The age of the mussel that has been nucleated• The environmental conditions of the culturing

farm

As an example of this last item, experienced cul-tivators know that the water quality at Shaoxingpearl farms is different from that of pearl farmsalong the Chang Jiang River.

Pearl farmers carefully choose mussels with shellnacre that shows good luster as the source of themantle tissue to be used in the nucleation process.As noted above, to achieve the best luster (andcolor), the technicians insert the pieces of tissue intothe posterior of the mantle lobe. This region of themantle also experiences the most growth. A youngmussel bears lustrous pearls, but as it becomes older(more than five or six years), the luster of the pearlgradually decreases as its size increases. Pearl cultur-ers claim that the water quality (probably the differ-ence in mineral content) of their farms is the key toproducing pearls with a shiny metallic luster, butthat regardless of the farm the metallic luster willdisappear if the cultured pearl is left in a mussel thatis more than five or six years old.

In addition to these four factors, the musselspecies itself will affect pearl luster. Pearls withvery fine luster are produced when the pieces ofmantle tissue are cut from the mantle of a C. plica-ta and inserted into the mantle of an H. cumingi.However, almost all of the pearls produced withthis combination have heavy surface wrinkles.

CONCLUSIONAnnual production of freshwater cultured pearls inChina is estimated at about 1,000 tons, with approxi-mately 650 tons usable in the jewelry trade. However,the present expansion of cultivation indicates a sub-


Figure 25. This contemporary jewelry takes advan-tage of the combination of unusual colors offered

by Chinese FWCPs. Jewelry courtesy of StreamCo.; photo © A.Takagi/Bexem Co. Ltd.

Figure 24. Chinese FWCPS occur in different tones,saturations, and combinations of white, orange,

and purple. Photo by Li Tajima Zansheng.

stantial increase within the next two or three years.Although more high-quality FWCPs are being pro-duced as cultivation methods improve, most of theChinese FWCPs are still of moderate to low quality.

The improvements in size, shape, surface condi-tion, luster, and color seen in recent years are theresult of many advances in the culturing materialsand techniques used. These include changing mus-sel species from C. plicata to H. cumingi, nucleationof younger (one-year-old) mussels, improvement inthe tissue nucleation (rolling a thinner piece of man-tle into a round shape and inserting fewer pieces intothe host mussel), a relatively longer culturing period,and a frequent change of culturing farms.

Bead-nucleation techniques also are being devel-oped, but our experience indicates that bead-nucle-ated FWCPs continue to represent a very small per-centage of the total production in China. Thisappears to be due to the technical difficulties andculturing costs involved. For example, bead nucle-ation doubles the labor required because both a beadand a piece of tissue must be inserted into the pock-et, whereas tissue nucleation requires only a singleaction to insert the piece of tissue. In any event, asdiscussed in Appendix A, the separation of bead-nucleated from tissue-nucleated cultured pearls, andof the tissue-nucleated product from its naturalcounterparts, is readily accomplished with contem-porary X-radiography techniques.

While this information represents the study ofseveral pearl operations and hundreds of FWCPs,the fact that China has many thousands of pearlfarms and produces tons of cultured pearls annuallymakes it impossible to provide a complete story.We believe, however, that the information we haveprovided is representative of the Chinese productseen in the market today and that the new nucle-ation and culturing techniques promise an even bet-ter product in the future.


Figure 26. Lavender is one of the distinctive colorsin which Chinese FWCPs occur. The rounds in thestrand are approximately 9.5 mm in diameter; thecultured pearl in the ring is 12.3 mm. Photo ©Harold & Erica Van Pelt.

ABOUT THE AUTHORS

Mr. Akamatsu is former manager of the Pearl ResearchLaboratory and currently general manager of the SalesPromotion Department, K. Mikimoto & Co. Ltd., Tokyo, Japan.Mr. Li, who started his Chinese freshwater cultured pearl busi-ness in 1985, is president of Stream Co., Tokyo and HongKong; in 1998, he established a pearl-processing operation inZhuji City, China. Mr. Scarratt is laboratory director at theAGTA Gemological Testing Center, New York; and Mr. Moses is vice president of Identification Services at the GIA Gem TradeLaboratory, New York.

ACKNOWLEDGMENTS

The authors express heart-felt appreciation to He Xiao Fa, directorof Shanxiahu Pearl Co. Ltd. in Zhuji City, and Lou Yong Qi, direc-tor of Echolou Pearl Co. in Zhuji City, for giving them the opportu-nity to visit several pearl farms, and for providing numerous FWCPsamples. The authors also gratefully acknowledge Mikio Ibuki, executive manager of the Japan Pearl Exporters Association(JPEA), for supplying Kasumiga cultured pearls. Last, the authorsthank Katsumi Isono, president of Miyake Nucleus ManufacturingCo. in Matsubara City, Osaka, for fashioning bead nuclei from tis-sue-nucleated “potato” FWCPs for the purposes of this research.


Cultured pearls form a significant portion of all gemmaterials traded. Yet the one nondestructive methodthat can be used to identify the growth technique orseparate cultured from natural pearls—X-radiogra-phy—is available only to a limited number of gemol-ogists who have access to the necessary equipment.Nevertheless, it is important that all gemologistsunderstand the principles behind X-radiography andits capabilities in pearl identification. While the gen-eral method and operating procedures have been pub-lished by, for example, Webster (1994) and Kennedy(1998), this box provides specific information regard-ing the use of X-radiography in the identification offreshwater cultured pearls (FWCPs) grown by a vari-ety of techniques in China. The information is basedon the experience of two of the authors (TMM andKS) with taking and interpreting tens of thousands ofpearl X-radiographs over the last two decades, manyof which were of Chinese FWCPs.

Pearl Structure. Both natural and cultured freshwaterpearls are formed of concentric layers, of variablethickness, that are comprised of aragonite and/or cal-cite along with some organic matter. As the pearlgrows, more organic matter may be accumulated dur-ing one period than another, as seen in figure A-1.Some pearls—natural or cultured by tissue nucle-ation—have a growth structure similar to thatbetween points A and B in figure A-1, whereas othershave one similar to that between points B and Cthroughout. Most Chinese freshwater cultured pearls(FWCPs) that are nucleated only with tissue also con-tain a characteristically shaped cavity near their cen-ter. If such samples are sawn adjacent to this cavity, itmay reveal itself only as a fine line (figure A-2). For amore complete explanation of the growth structure ofpearls, see chapter 22 of Webster (1994).

To better understand the identification criteriadiscussed below, it is important to note the less obvi-ous organic layers between points B and C in figureA-1, as well as the obvious ones. Note also the con-centric growth between A and B in figure A-1, and thestructures in figure A-2.

X-radiography Equipment. For more than 70 years,X-radiography has formed the backbone of pearl iden-tification. Fortunately for the industry, there are anumber (albeit limited) of gemologists with exten-sive experience in producing and interpreting X-radiographs. Although pearl X-ray units have gonethrough many incarnations, today there are severalindustrial units that are well suited to perform thetasks required for Chinese FWCP identification.

While we recognize that the latest digital or similarX-radiography units give the user a degree of conve-nience, it is the experience of these authors (TMMand KS) that the identification of Chinese FWCPsrequires a resolution that at this time is availableonly through the use of very fine-grain X-ray film—wet radiography. The instruments used by theauthors are Faxitron models 43855B and 43856A.These air-cooled units are powered by normal electri-cal outlets, have variable kV and mA control, andoffer an extended timed exposure capability. The dis-tance between the X-ray tube target and the sampleis adjusted by moving the shelving under the pearls.

Procedures. The samples should be placed in directcontact with a sheet of high-resolution fine-grainindustrial X-ray film; the film and the as-yet-uniden-tified pearls are then placed in a position—and at adistance—that will allow all the samples to be con-tained within the X-ray beam (figure A-3). Next,depending first on the size of the pearls, X-rays aregenerated for a specifically timed exposure at prede-termined kV and mA settings. Then, based on theinternal structures observed in the resulting X-radio-graph, the technician may increase or decrease the

APPENDIX A: IDENTIFYING CHINESE FRESHWATERCULTURED PEARLS BY X-RADIOGRAPHY

Figure A-1. In this thin section of a natural freshwaterpearl, the center of the pearl is located at the top left(A). Note the various stages of growth along the lineA-B-C. Between A and B is an evenly depositedarrangement of concentric layers, inside of which areradially arranged crystals. At B the structure abruptlychanges, with a large organically lined void that isfollowed by several yellow and dark, mostly organic,layers interspersed with the more crystalline (gray)layers toward the edge of the pearl (C).

A

B

C


exposure times, target-to-pearl distances, and kV andmA settings.

All X-radiographs are normally examined at mag-nifications between 2× and 10× (hence the need forfine-grained film) using a variety of back-illumina-tion techniques. The X-radiograph may show one ormore of the following features, depending on thenature of the sample:

1. If the sample was a coherent solid composed ofaragonite or calcite, without any organic mat-ter: The image would be simply an opaquewhite disc against a black background. That is,the aragonite or calcite would have absorbed theX-rays and left the film immediately below itunexposed (white), whereas the remainder of thefilm would have been fully exposed and thusblack when processed. This is how the shellbead portion of a bead-nucleated cultured pearlwould look, and is not uncommon for a non-nacreous (e.g., conch) “pearl.”

2. If the sample was aragonite or calcite with inter-nal organic material or voids: The image wouldreflect the difference in the ability of the X-rays topass through the aragonite or calcite, the organicmaterial, and any voids present. Organic layers andvoids pass X-rays more readily than calcium car-bonate does, so they reveal themselves on the pro-cessed X-ray film as dark gray to black lines orshapes set against the white background of the cal-

cium carbonate. If voids are present, the contrastbetween these and the calcium carbonate general-ly will be greater than that for organic material.

If one takes the more familiar example of ahuman bone contained within the flesh of thehuman body, a similar principle applies. The humanbone absorbs the X-rays more than the flesh that sur-rounds it and thus stands out clearly as “white”against the gray to black areas that comprise the flesh(organic). In addition, any fractures or fissures in thebone (voids) will appear black on the processed film.

Once the initial observations have been complet-ed, the technician takes additional X-radiographs,now optimized for the suspected type of pearl—natu-ral, cultured (bead or tissue nucleated), etc.—beingexamined, in several different directions, to provideimages that can be interpreted as characteristic of thesample in three dimensions.

The scattering of X-rays as they pass throughand around a pearl may at times reduce the qualityof the image. Two techniques that the authors havefound to be successful in absorbing the scattered X-rays (and thus enhancing the image) are: (1) fornecklaces, immersing the pearls in a scatter-reduc-ing fluid; and (2) for single pearls, surrounding thesides of the sample with a thin layer of lead foil.

Characteristics of Tissue-Nucleated and Bead-Nucleated Chinese FWCPs. X-radiographs of tis-sue-nucleated FWCPs will show features thatdepend to some extent on when they were grown.“Rice Krispie” tissue-nucleated Chinese FWCPsgrown in the 1970s typically have somewhattwisted internal organic structures and voids (fig-ure A-4, left). X-radiographs of more recentlygrown tissue-nucleated Chinese FWCPs—with

Figure A-2. In this sawn half of a knowntissue-nucleated cultured pearl, the slight dark linein the center (at B) is the only visual evidence of thetissue implant. Note, however, as in figure A-1 thevarying amounts of organic material (dark) associ-ated with the concentric growth structures.

A

B

C

Figure A-3. The samples (here, a baroque strandranging from 12.0 × 9.15 to 15.20 × 11.15 mm) areplaced on the film immediately below the X-raybeam in the Faxitron unit. Photo by E. Schrader.


their characteristic implant lines—were publishedby Scarratt et al. (2000; figure A-4, right). In bothcases, the X-radiographs are totally unlike those ofeither natural pearls (figure A-5) or of culturedpearls produced from a shell bead nucleus.

The X-radiographs of shell bead-nucleatedChinese FWCPs resemble those of shell bead-nucleated saltwater cultured pearls (figure A-6).Centrally located beads with no internal growthstructures are separated from the nacre overgrowthby a layer that is mostly organic. Any possible con-fusion with tissue-nucleated FWCPs caused bydark areas on the X-radiograph inside the area ofthe central bead would be dispelled by X-radio-graphs taken in other directions.

The X-radiographs of wax bead-nucleatedChinese FWCPs also show characteristic features(figure A-7). Each contains a nearly circular centralarea that is black or dark gray. Additional layers aredefined by fine black concentric growth structureswithin the white crystalline areas of the ChineseFWCP (which are not visible in figure A-7). Thereare similarities between the X-radiographic struc-

tures seen in this type of Chinese FWCP and thosesometimes observed in natural pearls. However, nat-ural pearls differ from Chinese FWCPs in that theyshow additional structures within the central area.

The short descriptions given here about the equip-ment needed, procedures, and expected results mustbe supplemented by operator experience—the mostimportant element.

Figure A-6. This radiographic image of shell bead-nucleated Chinese freshwater cultured pearls istypical of the images seen for this product.

Figure A-5. Natural pearls typically do notshow evidence of a nucleus, only the structuresthat indicate organic matter or voids. Notealso the concentric rings throughout this pearl.

Figure A-7. Recently produced wax bead-nucle-ated Chinese FWCPs have the characteristicradiographic structures shown here.

Figure A-4. The dark gray“twisted” structures shownon the left are typical of thetissue-nucleated ChineseFWCPs produced in the1970s. In the X-radiographon the right of more recentFWCPs, ovoids mark theoriginal tissue implant.


REFERENCESBosshart G., Ho H., Jobbins E.A., Scarratt K. (1993) Freshwater

pearl cultivation in Vietnam. Journal of Gemmology, Vol. 23,No. 6, pp. 326–332.

China producing nucleated rounds (1995) Jewellery News Asia,No. 129, pp. 56–58.

China starts pearling revolution (2000) Jewellery News Asia, No.186, p. 62.

Farn A. (1986) Pearls: Natural, Cultured and Imitation.Butterworths, London, p. 76.

Fukushima Y. (1991) The freshwater pearl in China. Pearls of theWorld II, Les Joyaux special edition, Shinsoshoku Co., Tokyo,pp. 127–134.

Hänni H. (2000) Gem news: Freshwater cultured “Kasumigapearls,” with Akoya cultured pearl nuclei. Gems &Gemology, Vol. 36, No. 2, pp. 167–168.

Hiratsuka T. (1985) The Chinese freshwater pearl. Pearls of theWorld, Les Joyaux special edition, Shinsoshoku Co., Tokyo,pp. 95–100.

Jobbins E.A., Scarratt K. (1990) Some aspects of pearl productionwith particular reference to cultivation at Yangxin, China.Journal of Gemmology, Vol. 22, No. 1, pp. 3–15.

Kennedy S.J. (1998) Pearl identification. Australian Gemmolo-gist, Vol. 20, No. 1, pp. 2–19.

Li H.P., Zhang X.P. (1997) Chapter 4: Nucleating operation. InDanshui Zenzhubang Yangyu [Freshwater Pearl MusselCultivation], Science Technology Literature Press, Beijing, pp.

36–67 (in Chinese). Li S.R. (1997) Chapter 2: Nucleus Inserting Operation, 2—Bead

nucleus inserting operation. In Danshui Zenzhu Peiyu Jishu[Freshwater pearl cultivation technique]. Jin Dun Press,Beijing, pp. 71–78 (in Chinese).

Matlins A. (1999) Large Chinese freshwater cultured pearls.Journal of the Accredited Gemologists Association, Winter99–00, pp. 1, 3, 5.

Roskin G. (2000) Are freshwater Chinese pearls being misrepre-sented? Jewelers’ Circular Keystone, Vol. 171, No. 3, pp. 36, 38.

Scarratt K., Moses T., Akamatsu S. (2000) Characteristics ofnuclei in Chinese freshwater cultured pearls. Gems &Gemology, Vol. 36, No. 2, pp. 100–102.

Statistics of fishery and cultivation (2000) Almanac of FisheryAgency. Ministry of Agriculture, Forestry and Fisheries,Tokyo.

Toyama T. (1991) Freshwater pearl—Status of, and future. Pearlsof the World II, Les Joyaux special edition, Shinsoshoku Co.,Tokyo, pp. 119–126.

Ward F. (1985) Pearl. National Geographic, Vol. 168, No. 2,August, pp. 192–223.

Webster R. (1994) Gems—Their Sources, Descriptions andIdentification, 5th ed. Rev. by P.G. Read, Butterworth-Heinemann Ltd., Oxford, England, 1026 pp.

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TWENTY YEAR INDEX1981–2000

SPECTRAL REFLECTANCE AND

FLUORESCENCE CHARACTERISTICS OF

NATURAL-COLOR AND HEAT-TREATED

“GOLDEN” SOUTH SEA CULTURED PEARLS

114 “GOLDEN” SOUTH SEA CULTURED PEARLS GEMS & GEMOLOGY SUMMER 2001

first marketed in 1993 with full disclosure that theywere treated (Vock, 1997). Details of the proprietaryprocess are not known, but it has been reported thatthe treatment, which is believed to be stable, isapplied to undrilled cultured pearls and involves theuse of heat without the application of dyes orbleaching (Vock, 1997). Inasmuch as the report didnot exclude chemicals other than bleach, it is possi-ble that chemicals also may be involved in thetreatment. It is probable that other companies aretreating “golden” pearls using a similar process.

The challenge for the gem and jewelry indus-try is to separate natural-color cultured pearls, ofany color, from treated ones (Sheung, 1998).Although, as noted above, drilled treated culturedpearls generally can be distinguished from natu-ral-color cultured pearls by microscopy (Hargett,1989), undrilled cultured pearls—especially in theabsence of obvious visual features—are much

By Shane Elen


A comparison study was made between the yellow and white nacre of the gold-lipped Pinctada maximaoyster shell and 65 yellow cultured pearls, both natural and treated color, produced from this mollusk. Theyellow nacre of this shell has a characteristic absorption feature in the UV region between 330 and 385 nm;the strength of this feature increases as the color becomes more saturated. White shell nacre fluoresces verylight blue or very light yellow to long-wave UV radiation, whereas yellow shell nacre fluoresces greenish tobrownish yellow or brown. Natural-color yellow cultured pearls from P. maxima exhibited absorption andfluorescence characteristics similar to those of the yellow shell nacre. In contrast, the absorption feature inthe UV was either weak or absent in yellow cultured pearls reportedly produced by a method involving heattreatment, and their fluorescence was generally very light blue or light yellow.

he popularity of “golden” cultured pearlsfrom the South Seas (figure 1) has increasedsteadily over the last 10 years (Vock, 1997;

“Prices of golden…,” 2000). As demand for thesecultured pearls has grown, treated-color “golden”cultured pearls have also entered the marketplace.A portion of the South Sea yellow cultured pearlsharvested are well shaped with few blemishes butwith less desirable color—either very light(Federman, 1995) or uneven. The most commonmethods used to produce or enhance yellow col-oration in South Sea “golden” cultured pearlsinvolve treatment with a chemical or an organic dye.The fact that so many different chemicals and dyescould be used for this purpose complicates a compre-hensive study of these treatment methods.However, inorganic chemicals are routinely identi-fied using EDXRF; and dyes, since they usually areapplied after the pearls are drilled, generally are easyto identify with magnification.

The Ballerina Pearl Co. (New York City) devel-oped a method in the early 1990s to treat thesepoorly colored South Sea cultured pearls to producea more uniform and desirable yellow. These were

T

“GOLDEN” SOUTH SEA CULTURED PEARLS GEMS & GEMOLOGY SUMMER 2001 115

more difficult to identify. The present reportcompares heat-treated yellow cultured pearls tonatural shell nacre and natural-color yellow cul-tured pearls from the Pinctada maxima to identi-fy criteria that can be used to separate treatedfrom natural-color material, especially when thesamples are undrilled.

BACKGROUNDThe gold-lipped P. maxima oyster has a characteris-tic yellow to “golden” nacre inside the shell alongthe periphery of the white nacreous region (Gervisand Sims, 1992, p. 4; again, see figure 1). Pearls pro-duced from this oyster, either natural or cultured,are typically white, “silver,” or yellow (South SeaPearl Consortium, 1996) and include so-called“golden” pearls.

The post-harvest color treatment of culturedpearls, of any color, falls into two categories: prior todrilling and after drilling. Heat treatment (Vock,1997) and gamma irradiation (Ken-Tang Chow,1963) may be performed pre- or post-drilling. Asnoted above, however, dyes and chemicals typicallyare used only after drilling (Komatsu, 1999), to facil-itate their entry parallel to the nacre layers.Generally, such treatments affect the organic mate-rial (i.e., conchiolin) between the nacre layers; theyhave less influence on the crystalline nacre (Gau-thier and Lasnier, 1990).

The most obvious indication of these treatments(with the exception of irradiation) is an unusualcolor concentration in the form of a colored layer(visible in the drill hole) or a colored spot or streakvisible on the surface (Komatsu, 1999). Color fromdyes or chemicals typically becomes concentratedin surface defects such as cracks, pits, or blemishes(Newman, 1999, p. 94). Dimples or protrusions inthe nacre are particularly likely to exhibit concen-trations of color. These areas are often more porous(as indicated by a cloudy or milky appearance priorto treatment), which allows the dye or chemical tobecome concentrated (T. Moses, pers. comm.,2000). These features sometimes are eye-visible, butusually they can be detected only with microscopy.

Typically, detection of a treated yellow color inundrilled cultured pearls relies on the presence ofsurface color concentrations. When such featuresare absent, however, identification is more of a chal-lenge. Inasmuch as the Ballerina process is appliedprior to drilling, this is the situation for yellow cul-tured pearls treated by this technique.

Due to the nature of the chemicals and dyes typ-ically used in most post-drilling treatments, manycolor-treated natural and cultured pearls can beidentified using X-ray fluorescence (XRF) or Ramanspectrometry (see box A). However, the author didnot find these techniques useful for the heat-treated“golden” pearls tested for this study. Thus, the pur-

Figure 1. These nat-ural-color and heat-treated culturedpearls range from12.5 to 13.6 mm;the natural-colorcultured pearls areon the top right andbottom left. Notethe area of “golden”nacre along theperiphery of thewhite nacreousregion in the gold-lipped Pinctadamaxima shell (18.0cm in diameter).Photo by MahaTannous.

Figure A-1. The iodine (I) peaks in this energy-dispersive X-ray fluorescence (EDXRF) spec-trum of a yellow Akoya cultured pearl indi-cate chemical treatment.

Figure A-2. In this Raman spectrum of an orangyyellow Akoya cultured pearl, the series of peaksabove 1085 cm-1 indicate treatment with anorganic dye.

Figure A-3. In a UV-Vis (ultraviolet-visible)reflectance spectrum, an absorption maximumat 700 nm is characteristic of natural-colorblack cultured pearls from the Pinctada mar-garitifera oyster.

Figure A-4. This luminescence spectrum of a culturedblack pearl from Pinctada margaritifera shows fluo-rescence peaks at 617 and 676 nm due to porphyrins,which are responsible for the reddish brown fluores-cence to 365 nm UV or 405 nm blue light.


Advanced testing often can be used to identify color-treated cultured pearls. These techniques include X-ray fluorescence (XRF), Raman and luminescencespectrometry, and UV-Vis spectrophotometry. XRFis useful for detecting the presence of inorganictreatments such as silver salts (black) or iodine (yel-low; figure A-1). In most cases, organic treatmentsand biological pigments cannot be detected by thismethod, but their presence can sometimes be deter-mined using Raman spectrometry (figure A-2). UV-

Vis spectrophotometry frequently is used to identifythe presence of chromophores responsible for natu-ral coloring in Tahitian black cultured pearls, asindicated by an absorption at 700 nm (Komatsu andAkamatsu, 1978; figure A-3). Luminescence can ver-ify the presence of porphyrins (Miyoshi et al., 1987)responsible for the reddish brown fluorescenceobserved in natural-color black cultured pearls origi-nating from the Pinctada margaritifera, Pteria ster-na, and Pteria penguin oysters (figure A-4).

BOX A: ADVANCED IDENTIFICATION OF COLOR TREATMENTSIN NATURAL AND CULTURED PEARLS


pose of the present research was to determine othernondestructive spectral or fluorescence characteris-tics that could be used to aid in the identification ofheat-treated yellow cultured pearls from the P.maxima that either are undrilled or have drill holesthat are inaccessible for examination.

For convenience and brevity, natural-color yel-low cultured pearls will henceforth be abbreviatedas NYCPs, and reportedly heat-treated yellow cul-tured pearls as HTYCPs. Note, too, that the hue,tone, and saturation terms used to describe the col-ors of the shell and cultured pearl samples are basedon the new (2000) GIA pearl grading system.

MATERIALS AND METHODSTo establish the characteristics of known untreatedmaterial, we obtained a total of 42 samples of nacrefrom seven gold-lipped P. maxima shells that origi-nated from Australia (2 shells), the Amami Islands inJapan (2), and the Philippines (3). The samples, eachapproximately 9 mm in diameter, were removedwith a diamond saw while the shells were com-pletely immersed in water, since overheating couldaffect their color (Webster, 1994) and thus their fluo-rescence or spectral characteristics. Two samples ofwhite nacre and four samples of yellow nacre wereobtained from each shell, for a total of 14 whitenacre and 28 yellow nacre samples.

In addition, 53 NYCPs, ranging from 9.1 to 15.7mm, were obtained from several reputable sources.They were reportedly from Indonesia (5), thePhilippines (23), Japan (3), Australia (6), and the“South Seas” in general (16). Forty-five wereundrilled and eight were drilled. Twelve undrilledtreated-color yellow cultured pearls, which werereportedly heat treated, were also obtained for thestudy; they ranged from 11.8 to 13.1 mm. We believethat these samples originated from the gold-lippedvariety of the P. maxima; we could not confirmwhether the process has been applied to culturedpearls from the silver-lipped P. maxima. No strongly

saturated yellow cultured pearls of known pedigree,natural or treated, were available for characterization.

All of the cultured pearls were examined with aGIA Gem Instruments Mark VII microscope usingfluorescent and fiber-optic lighting. Initially sixNYCPs and six HTYCPs were analyzed with aRenishaw 2000 Ramascope laser Raman microspec-trometer and a Thermo Noran Spectrace 5000EDXRF spectrometer. Inasmuch as neither tech-nique revealed any distinct differences between thenatural- and the treated-color samples, further test-ing by Raman and EDXRF was discontinued.

UV-Vis reflectance spectra and fluorescenceobservations were obtained for each sample using aHitachi 4001 spectrophotometer and a UVP modelB100 AP long-wave ultraviolet lamp. Reflectancespectra were collected from 250 to 2500 nm,although only the pertinent data range (i.e., 250–700nm) is illustrated in this article. At least two spectrawere obtained in different regions for each culturedpearl that showed uneven color or fluorescence dis-tribution. A total of 162 reflectance spectra werecollected: 42 on the shell nacre samples, 94 on thenatural-color cultured pearls, and 26 on the treatedcultured pearls. Acquisition of luminescence spec-tra with a Spectronic AB2 luminescence spectrome-ter was unsuccessful, due to instrument configura-tion, sample shape, and the generally desaturatedfluorescence colors. Therefore, fluorescence colorand distribution were observed visually in a dark-ened room with the aid of UV contrast goggles.

RESULTSVisual Appearance. Fourteen of the shell nacre sam-ples were white, and 28 ranged from light to darkyellow (see, e.g., figure 2). The natural-color cul-tured pearls ranged from very light yellow to orangyor greenish yellow (see, e.g., figure 3); a few exhibit-ed slightly uneven color distribution. The HTYCPsranged from light yellow to orangy yellow (see, e.g.,figure 4), with the majority being light yellow.

Figure 2. These five samples, each about 9 mm indiameter, show the range of color seen in thePinctada maxima shell nacre samples. Photo byMaha Tannous.

Figure 3. The natural-color yellow cultured pearlsranged from very light yellow to orangy (as shownhere) or greenish yellow. These pearls are 11.6–13.6mm in diameter. Photo by Maha Tannous.

Small, localized spots of concentrated color werevisible in 10 of the 12 HTYCPs, with either theunaided eye or magnification (figure 5). The remain-ing two did not exhibit any visible or microscopicevidence of treatment.

UV-Vis Reflectance Spectra and Fluorescence. ShellNacre Samples. The UV-Vis spectra revealed adecrease in reflectance due to absorption between330 and 460 nm for all 28 yellow shell nacre sam-ples as compared to the samples of white shellnacre. This broad region of absorption is actuallycomposed of two features: one in the UV regionfrom 330 to 385 nm, with a maximum between 350and 365 nm; and the other in the visible region from385 to 460 nm, with a maximum between 420 and435 nm. The spectra of the white shell nacre sam-ples showed no absorption features in this broadregion. Examination of the reflectance spectra for aseries of five samples that ranged from white todark yellow revealed an increase in the generalabsorption between 330 and 460 nm as the strengthof the yellow coloration increased (figure 6).

Typically, dark yellow shell nacre exhibitedmoderate brown, greenish brown, or greenish yel-low fluorescence, and light yellow shell nacre flu-oresced light brown or light yellow (see, e.g., fig-ure 7). Most of the white shell nacre samplesshowed moderate-to-strong very light blue fluo-rescence, although some appeared to exhibit aslight trace of yellow.

Natural-Color Cultured Pearls. The spectra forthese samples (figure 8) exhibited absorption charac-teristics similar to those of the yellow shell nacre,except that the maximum in the UV varied from350 to 385 nm. All but four of the 94 spectraobtained on these samples exhibited the two absorp-tion features between 330 and 460 nm. In the fourspectra that did not show these features, the regions

analyzed were white areas on unevenly coloredsamples; and these results were similar to thereflectance spectra obtained for white shell nacre.As the yellow color of the cultured pearls increasedin saturation, the long-wave UV fluorescence pro-gressed from light yellow or light brown, to greenishyellow, greenish brown, or brown.

Heat-Treated Cultured Pearls. Five of the 26reflectance spectra obtained from the HTYCPs


Figure 4. The heat-treated yellow cultured pearlsranged from light yellow to moderate orangy yel-low. The samples shown here are 11.3–12.6 mm indiameter. Photo by Maha Tannous.

Figure 5. Small spots of concentrated color are evi-dent within blemishes on this yellow culturedpearl that reportedly has been heat treated.Photomicrograph by Shane Elen; magnified 5×.

Figure 6. These reflectance spectra of five shellnacre samples—ranging from white through darkyellow—show increasing absorption from 330 to460 nm as the color intensifies. Note in particularthe increasing absorption in the UV region from330 to 385 nm.

exhibited a weak absorption feature in the UV regionaround 345 nm (see, e.g., figure 9). These spectra rep-resented five of the 12 treated cultured pearls stud-ied. Spectra taken from other areas on these samefive HTYCPs, and from the remaining sevenHTYCPs, exhibited very weak or no absorption inthe UV region. All 26 spectra showed an absorptionfeature in the blue region between 415 and 430 nm.

Generally, the fluorescence of the HTYCPs wasslightly uneven, and appeared unrelated to the dis-

tribution of bodycolor. In one HTYCP, however,fluorescence did appear to be related to the unevendistribution of the yellow color: Light yellow andlight brown fluorescence corresponded directly toareas of light yellow and light orangy yellow. Eightof the HTYCPs, which were light in tone and satu-ration, fluoresced moderate to strong light yellow;two—also light in tone and saturation—exhibited avery light blue fluorescence. The sample with the


Figure 8. As was the case with the shell nacre sam-ples, the reflectance spectra of the natural-coloryellow cultured pearls showed increasing absorp-tion in the 330–460 nm region with greater satura-tion of color.

Figure 9. The reflectance spectra of the heat-treatedyellow cultured pearls revealed very weak or noabsorption in the 330– 385 nm region. The presenceof a weak UV absorption feature around 345 nmsuggests that the orangy yellow cultured pearlexhibited some natural yellow coloration prior totreatment.

Figure 7. The typical fluorescence reactions of natural- and treated-color cultured pearls when exposedto 365 nm (long-wave) UV radiation are illustrated here. Shown in normal lighting (left in each pair)and with long-wave UV (right) are: (A) white shell nacre, (B) yellow shell nacre, (C) 13.6 mm natural-color light yellow cultured pearl, (D) 12.5 mm natural-color orangy yellow cultured pearl, (E) 12.6 mmheat-treated light yellow cultured pearl, and (F) 12.6 mm heat-treated orangy yellow cultured pearl.Normal lighting photos by Maha Tannous; fluorescence photos by Shane Elen.

A

B

C

D

E

F

most saturated orangy yellow bodycolor fluoresceda light brownish orange. The spots of concentratedcolor seen in some HTYCPs (see figure 5) fluoresceda strong orange to long-wave UV.

DISCUSSIONConfirmation of Reported Origin of Color. One ofthe main challenges of performing a study of thiskind is obtaining samples of known species andcolor origin. Ideally for pearls of natural color, wit-nessing the removal of the pearl from the oysterwould be the method of choice. However, this is notalways practical, so instead we must look to veryreliable sources. Similarly, obtaining pearls treatedby specific methods also can be very challenging.

None of the cultured pearls represented as beingof natural yellow color showed any visible indica-tions of treatment, whereas most of the culturedpearls reported to be heat treated did exhibit somevisible evidence in the form of spots with concen-trated color. In most cases, too, there was a distinctdifference in reflectance spectra between yellow

cultured pearls stated to be natural color and thosethat were reportedly heat treated. In addition, thosestated to be natural color exhibited reflectance andfluorescence characteristics similar to the samplesof shell nacre of similar color. These findings wouldappear to support the reported color origins for thecultured pearl samples used in this study.

Although no chemical study of the zoochrome (anaturally occurring pigment molecule found in theanimal kingdom; Needham, 1974) was performed,the reflectance and fluorescence results indicatethat the yellow coloration in P. maxima shells andNYCPs appears to be due to a common zoochromeregardless of their geographic origin.

Spectral Reflectance Characteristics. A broadabsorption between 330 and 460 nm in thereflectance spectra was seen in the yellow nacrefrom both the gold-lipped P. maxima shell and theNYCP samples (figures 6 and 8), and thus appears tobe characteristic of natural-color yellow nacre pro-duced by this species. The strength of this absorp-tion appeared to increase as the color became moresaturated. The 420–435 nm maximum (in the blueregion of the visible spectrum) is typical ofreflectance spectra for yellow objects (Lamb andBourriau, 1995), and is responsible for the yellowcolor observed. Although UV absorption is not nec-essary to produce yellow coloration, it does appearto be related to the same zoochrome that is respon-sible for the absorption in the blue region of the visi-ble spectrum. The absence of this absorption maxi-mum in the UV reflectance spectra obtained fromwhite areas on unevenly colored cultured pearls isconsistent with the reflectance results obtained forwhite shell nacre.

The HTYCPs exhibited an absorption in theblue region, as would be expected for a yellow cul-tured pearl, but there was a significant difference inthe strength of UV absorption between similarlycolored natural and treated cultured “golden” pearls(figure 10). The absence of the UV absorption fea-ture in the HTYCPs indicates that the cause of theiryellow coloration is different from that of theNYCPs tested. The fact that some areas of the treat-ed cultured pearls showed a weak UV absorptionfeature suggests that these areas were a light yellowprior to treatment.

Ultraviolet Fluorescence. Fluorescence can be avaluable yet challenging identification technique,since many of the effects and color differences are


Figure 10. These reflectance spectra of natural andtreated light yellow (top) and orangy yellow (bot-tom) cultured pearls show a distinct difference inabsorption in the 330–385 nm region. Note thelack of absorption in this region shown by thetreated-color samples.

quite subtle and can vary depending on the type oflong-wave UV source used. It is important toobserve the relationship between (1) the tonal distri-bution of the yellow color, and (2) the distributionand hue of the fluorescence (again, see figure 7). Forthe natural-color samples, the distribution of fluo-rescence matched the evenness or unevenness ofthe color distribution: An even yellow distributioncorresponded to an even fluorescence distribution,and uneven color showed uneven fluorescence. Aneven color distribution with a patchy fluorescenceis indicative of treatment. In lighter samples, how-ever, slight tonal variations in nacre color can bequite difficult to see compared to the more obviouspatchy fluorescence.

In addition, the fluorescence colors emitted byboth natural- and treated-color light yellow cul-tured pearls can be similar, and thus they are lessreliable as an indicator of treatment. The exceptionto this is the very light blue fluorescence observedin natural white nacre and in some light yellowHTYCPs. The fact that no NYCPs of light yellowcolor exhibited this fluorescence color would implythat the treated-yellow sample was originallywhite. (Caution must be observed, however,because some long-wave UV lamps emit enoughblue visible light to render this observation unreli-able.) The HTYCPs also lacked the greenish fluo-rescence component noted in many of the yellowshell nacre samples and NYCPs. Neither theNYCPs nor the yellow shell nacre exhibited thestrong orange fluorescence seen in the spots of con-centrated color of some of the HTYCPs; therefore,distinct spots of strong orange fluorescence wouldindicate treatment.

Inasmuch as the details of the heat-treatmentprocess are unavailable, the effect that heat treat-ment might have on the individual componentsthat contribute to fluorescence (i.e., conchiolin,aragonite plates, and pigments) was not investigat-

ed. It has been reported that the fluorescence of con-chiolin can be affected by certain treatments (S.Akamatsu, pers. comm., 2001). However, the differ-ences in fluorescence between natural- and treated-color cultured pearls may result from a combinationof these components and not necessarily from anyone component in particular.

Identification of Heat-Treated Yellow CulturedPearls. Table 1 summarizes key identificationcharacteristics for natural-color and heat-treatedyellow cultured pearls produced by the P. maximaoyster. As indicated below, the ease with whichHTYCPs can be identified depends greatly onwhether the original cultured pearl had even oruneven color.

1. An HTYCP that exhibited white and yellowareas prior to treatment is likely to be the easiestto separate from natural color. After treatment,the white areas would appear yellow but wouldexhibit the UV spectral characteristics of whitenacre; that is, the UV absorption characteristic ofyellow nacre between 330 and 385 nm would beabsent. In this type of treated cultured pearl, areasthat formerly were white fluoresce a lighter colorthan do the yellow zones. The uneven fluores-cence also may contrast with an even yellow col-oration of the treated cultured pearl.

2. An HTYCP that exhibited evenly distributed,very light color prior to treatment may exhibit aUV absorption feature that is too weak for itsapparent color (figure 10). Also, the fluorescencecolor might appear too light for the apparent toneand saturation of the treated cultured pearl.

3. Probably the most difficult to identify would beHTYCPs that were originally unevenly coloredlight and dark yellow. Nevertheless, this type ofHTYCP is likely to exhibit uneven fluorescence,possibly in contrast to an even yellow coloration.


TABLE 1. Summary of identification characteristics for natural-color and heat-treated yellow cultured pearls produced by P. maxima.

Nacre UV absorption Visible absorption Fluorescence to long-wave UV Commentscolor feature feature

(330 –385 nm) (385–460 nm)

Natural white None None Moderate to strong; very light Generally very light blue blue or very light yellow fluorescence

Natural yellow Distinct to strong Present Moderate; light yellow or light Even distribution of bodybrown, to greenish yellow, color will be accompanied greenish brown, or brown by even fluorescence

Heated yellow None to weak Present Moderate to strong; light yellow, Even distribution of body very light blue, or light brownish color may be accompaniedorange by uneven fluorescence

Again, the UV absorption feature would likelyappear too weak for the apparent color of thetreated cultured pearl.

If heat-treated cultured pearls are subsequentlydrilled, the color may appear to be concentrated inthe surface layers of nacre when observed throughthe drill hole (T. Moses, pers. comm., 2000).

CONCLUSIONAs “golden” cultured pearls from P. maximabecome increasingly popular in the marketplace(figure 11), there is growing incentive to treat off-color cultured pearls to produce these rich yellow toorangy yellow colors. As a result, the separation oftreated-color from natural-color pearls has become aconstant challenge for the gemologist. Althoughcolor treatment is relatively straightforward to iden-tify in many drilled cultured pearls because of dis-tinctive color differences in the layers visible

through the drill hole, certain treatments—especial-ly heat treatment—may be very difficult to detectin some undrilled cultured pearls.

The present study of white and yellow shellnacre from gold-lipped P. maxima shells showed acharacteristic increase in absorption between 330and 385 nm in the UV spectrum as tone and satura-tion increased from white to dark yellow. Thisabsorption appears to be related to the zoochromeresponsible for absorption in the blue region, whichresults in the yellow color of the nacre. The changein absorption with increasing tone and saturationwas accompanied by a similar change in long-waveUV fluorescence, which progressed from very lightblue or very light yellow, to light yellow or lightbrown, to greenish yellow, greenish brown, orbrown as the colors of the shell nacre sampleschanged from white to dark yellow.

NYCPs from the P. maxima oyster exhibitedcharacteristics similar to those of the yellow shell


Figure 11. Large, fine“golden” cultured pearlsare a popular item inthe jewelry mix. Thenatural-color culturedpearls in this strandrange from 13.0 to 17.3mm. Courtesy of Tara &Sons, New York; photo ©Harold & Erica Van Pelt.

nacre. However, the UV reflectance and fluores-cence properties of HTYCPs of comparable colorappeared more like those of very light yellow orwhite nacre. Although only 12 treated sampleswere obtained for the study, all 12 lacked the UVabsorption feature characteristic of natural yellowcolor in P. maxima. Therefore, the fluorescenceand, more importantly, the absence of UV absorp-tion can help identify heat-treated undrilled “gold-en” cultured pearls.

Given that the UV absorption feature is a charac-teristic of natural-color yellow nacre in P. maxima,the absence of this feature would indicate a treatedyellow color regardless of the treatment method used.Unfortunately, without further study of chemicallyprocessed or dyed “golden” pearls, we cannot statethat the presence of this feature proves that the coloris natural. Fortunately, these latter methods typicallyare applied to drilled cultured pearls and thus generallyare easier to identify.

REFERENCES

Federman D. (1995) Gem Profile: Philippine pearl—The quest forgold. Modern Jeweler, Vol. 94, No. 1, pp. 11–12.

——— (1998) The ABCs of pearl processing. Modern Jeweler, Vol.97, No. 3, pp. 53–57.

Gauthier J-P., Lasnier B. (1990) La perle noire obtenue par traite-ment a l’argent. Revue de Gemmologie a.f.g., No. 103, pp.3–6.

Gervis M.H., Sims N.A. (1992) The Biology and Culture of PearlOysters (Bivalvia: Pteriidae). International Center for LivingAquatic Resources Management Contribution No. 837,Studies and Reviews 21, 49 pp.

Hargett D. (1989) Gem Trade Lab notes: Pearls—“Pinked.” Gems& Gemology, Vol. 25, No. 3, p. 174.

Ken-Tang Chow (1963) Process for irradiating pearls and productresulting therefrom. U.S. Patent 3,075,906, issued January 29.

Komatsu H. (1999) The identification of pearls in Japan—A sta-tus quo summary. Journal of the Gemmological Society ofJapan, Vol. 20, No. 1–4, pp. 111–119.

Komatsu H., Akamatsu S. (1978) Studies on differentiation oftrue and artificially coloured black and blue pearls. Journal ofthe Gemmological Society of Japan, Vol. 5, No. 4, pp. 3–8.

Lamb T., Bourriau J. (1995) Color: Art & Science. Darwin CollegeLectures, Cambridge University Press, figure 12g, p. 86.

Miyoshi T., Matsuda Y., Komatsu H. (1987) Fluorescence frompearls and shells of black-lip oyster, Pinctada margaritifera,and its contribution to the distinction of mother oysters usedin pearl culture. Japanese Journal of Applied Physics, Vol. 26,No. 7, pp. 1069–1072.

Needham A.E. (1974) Zoophysiology and Ecology 3: The Sig-nificance of Zoochromes. Springer-Verlag, Berlin.

Newman R. (1999) Pearl Buying Guide, 3rd ed. InternationalJewelry Publications, Los Angeles.

Prices of golden South Sea pearls likely to rise. (2000) JewelleryNews Asia, No. 192, August, pp. 45, 59.

Sheung B. (1998) Concern about treatments rises. Jewellery NewsAsia, No. 168, March, pp. 49–52.

South Sea Pearl Consortium (1996) Guide to South Sea cul-tured pearl quality. Modern Jeweler, Vol. 95, No. 9, specialsupplement.

Vock A. (1997) Disclosure needed for a healthy industry.Jewellery News Asia, No. 158, October, pp. 52–54.

Webster R. (1994) Gems: Their Sources, Descriptions andIdentification, 5th ed. Revised by P. G. Read, Butterworth-Heinemann, Oxford, England, 1026 pp.


ABOUT THE AUTHOR

Mr. Elen is a research gemologist at GIA Research,Carlsbad, California.

ACKNOWLEDGMENTS: The author thanks the followingpersons for providing samples of cultured pearls andshells for this study: Alex Vock of ProVocative Gems,New York; Jacques Branellec of Jewelmer International,the Philippines; Salvador Assael of Assael International,New York; Terry D’Elia of D’Elia & Tasaki Co., New York;Nicholas Paspaley of Paspaley Pearling Co., Darwin,Australia; and David Norman of Broome Pearls Pty,Broome, Western Australia. Thanks also to Dr. PeterBuerki of GIA Research and Matt Hall of the GIA GemTrade Laboratory, for helping collect some of the spec-troscopic data; to Karin Hurwit and Cheryl Wentzell ofthe GIA Gem Trade Laboratory for aiding with colordetermination; and to Tom Moses of the GIA Gem TradeLaboratory, Dr. Jim Shigley of GIA Research and Shigeru Akamatsu, former manager of the Pearl Research Laboratory and currently general manager,Sales Promotion Department, at K. Mikimoto and Co.Ltd., Tokyo, for their constructive comments.

A NEW METHOD FORIMITATING ASTERISM

124 NOTES & NEW TECHNIQUES GEMS & GEMOLOGY SUMMER 2001

Kumaratilake, 1997, 1998), asterism has never beenobserved in many gemstones and is very rare in oth-ers. The presence of asterism in a gemstone can addsignificant value, especially if it occurs in a materialin which it has not previously been observed, suchas sinhalite (figure 1). Collectors of phenomenalgems have been known to pay handsomely for sucha stone, even if the gem material itself is unattrac-tive, or otherwise of little value.

Many methods have been used over the years toimitate asterism. These include: engraving a seriesof intersecting parallel lines on the back of a trans-parent cabochon which is then covered by a reflec-tive backing, or adding a thin engraved metallicplate to the back of a transparent cabochon (figure 2;see also Hurlbut and Kammerling, 1991); or using adiffusion process to put fine, oriented rutile needlesin a thin layer just under the surface of a cabochon(figure 3; Fryer et al., 1985). These star imitationscan be quite effective, but usually they are foundonly in gem materials that are known for asterism,such as rubies and sapphires.

Therefore, we were surprised to learn that anevidently new process was being used to create theappearance of asterism in gems that had not shownthis phenomenon previously. The first such stonesseen at the GIA Gem Trade Laboratory had beenrepresented to our client as rare examples of stars inunusual materials. Some of these stars showed asmany as 15 or 16 rays. Subsequently, we receivedmore asteriated stones, many of which were

By Shane F. McClure and John I. Koivula


NOTES & NEW TECHNIQUES

sterism and chatoyancy (i.e., the phenome-na of stars and cat’s-eyes, respectively) canpotentially occur in almost any gemstone.

Chatoyancy will occur if a sufficient volume andconcentration of acicular (needle-like) inclusionsline up parallel to one another within a gem materi-al, and the gem material then is cut into a properlyoriented cabochon. To create asterism, these con-centrations of needles must line up in more thanone direction— almost always in specific relation-ship to crystallographic axes—which gives rise tostars with four, six, and sometimes more rays.Chatoyancy can actually be caused by mechanismsother than acicular inclusions, such as the fibrousstructure in some cat’s-eye opal, or by other phe-nomena, such as the oriented adularescence in cat’s-eye moonstone (Hurlbut and Kammerling, 1991).For those not familiar with phenomena such asasterism and adularescence in gems, a good generalreference is Webster’s Gems (1994).

Nevertheless, even though the potential forasterism exists in almost any gemstone (see, e.g.,

Several gems were recently examined that showedstars with an unnatural appearance or an unusualnumber of rays. Asterism in some of these gem materi-als is very rare, or has not been seen previously by theauthors. Microscopic examination revealed that these“stars” were produced by using what appeared to be arough polish to scratch lines in an oriented fashiononto the upper surface of the cabochons.

A

NOTES & NEW TECHNIQUES GEMS & GEMOLOGY SUMMER 2001 125

opaque, that represented an array of different mate-rials. One even sported a double star. Most of thestars showed essentially straight rays, but in somecases the rays were obviously curved down the sidesof the cabochon (figure 4). These stones were sup-plied to us by three dealers from three very differentlocations (Louisville, Colorado; Bangkok, Thailand;and Falls Church, Virginia), and were purported to

be from Sri Lanka and India. Because of the types ofgem materials involved, the superficial appearanceof the stars, and the odd number and orientation ofsome of the rays in the stars, the dealers suspectedthat the asterism had been artificially created. Weconducted the present study to learn more aboutthis new technique and to establish the best meansof identifying this imitation asterism.

Figure 1. This 6.17 ctsinhalite, a gemstonethat has not beenreported to displayasterism, showed avery unusual 11-rayed star that ulti-mately proved to bemanufactured. Photoby Maha Tannous.

Figure 2. Oriented lines engraved on this thinmetal plate give the appearance of asterism in thesynthetic ruby cabochon to which it is attached.Photomicrograph, taken through the dome of thecabochon, by John I. Koivula; magnified 30×.

Figure 3. This very fine, unnatural-looking silk (sim-ilar in appearance to the silk found in flame-fusionsynthetic star rubies or sapphires) is typically seenin a star created by diffusion treatment. Photo-micrograph by John I. Koivula; magnified 40×.


MATERIALS AND METHODSAltogether, we examined a dozen stones that dis-played evidence of this new method of imitatingasterism. We studied one each of sinhalite, cassi-terite, chrysoberyl, and garnet, and one stone thatwas represented to be scheelite but turned out tobe a member of a series of naturally radioactiverare earth–bearing minerals, possibly samarskite.Chrysoberyl is well known for chatoyancy, but itrarely shows asterism. Star garnet is relativelycommon, but cat’s-eye garnet is rare. The authorshave not seen examples of either phenomenon in

sinhalite, cassiterite, and scheelite (or samarskite).The balance of the cabochons were rutile, inwhich natural chatoyancy is occasionally seen (fig-ure 5) and asterism is reported to be very rare(Kumaratilake, 1997).

The 12 cabochons in this study ranged from 3.29ct to more than 20 ct; all were oval or round andsemi-transparent to opaque.

All of the gem materials were identified by stan-dard gemological procedures. To determine the causeof the asterism, we used a GIA Gem InstrumentsMark VII Gemolite gemological microscope, at mag-nifications up to 45×, with fiber-optic illumination.

RESULTS AND DISCUSSIONEach stone displayed a star that had as few as sixrays (in the case of the chrysoberyl), to more than adozen rays (in the case of several rutiles). The garnetshowed a double star, one with four rays and theother with eight. The first thing anyone familiarwith natural asterism will notice is the unusualappearance of most of these stars. In many of thestones, the stars had too many rays and the rayswere not symmetrical (figure 6). Many stars also dis-played an unusual number of rays, such as eight or10, or an odd number such as 11 (again, see figure 1),which is not typical for any material. Also, theasterism appeared to be very superficial, even instones that were almost transparent, whereas trueasterism usually has depth to it.

Microscopic examination quickly identified the

Figure 4. This rutile cabochon displayed at least 16rays, most of which showed a noticeable curve asthey approached the girdle. Photo by Maha Tannous.

Figure 6. The stars made by the “scratching” pro-cess described here often displayed asymmetricalrays, such as in this 17.08 ct cassiterite that showsnine rays. Photo by Maha Tannous.

Figure 5. The eye of this natural cat’s-eye rutileshows a very dense concentration of needles thatare clearly inside the stone. Photomicrograph byJohn I. Koivula; magnified 45×.

NOTES & NEW TECHNIQUES GEMS & GEMOLOGY SUMMER 2001 127

source of the asterism: oriented, coarse, parallellines scratched on the domed surfaces of the stones(figure 7). At first one might think the lines werethe result of a bad polishing job, but close inspec-tion revealed that this “bad polish” was deliberate.By making the lines coarse and keeping them paral-lel in certain directions, the treater was able to usethem to reflect light in essentially the same waythat natural subsurface needle-like inclusions do.

As mentioned above, some of the stones dis-played too many rays or an unnatural number ofrays, so that the asterism was not believable. In onecase, however, the illusion was very well executed.A 3.29 ct chrysoberyl showed an almost perfectlysymmetrical six-rayed star (figure 8). The authorshave seen a few examples of chrysoberyl with a nat-ural six-rayed star over the years (figure 9), but theyare so rare that most references do not evenacknowledge their existence.

Perhaps the most interesting stone in our sam-ple group was a 4.28 ct purplish red garnet that dis-

played a double star, that is, two stars adjacent toone another (in contrast to multiple stars that man-ifest themselves in different areas of the stone).Double stars have been noted in some corundums(Moses et al., 1998), and multiple stars actually arecommon in some materials, such as quartz (see,e.g., Johnson and Koivula, 1999). To our knowl-edge, though, no such double star has been reportedin garnet. Even more suspicious was the fact thatone of the stars had four rays and the other hadeight. The authors are not aware of any reports ofdouble stars with this kind of asymmetry. In thiscase, microscopic examination revealed that thefour-rayed star was natural, and the eight-rayed starwas manufactured by the method described above.The four-rayed star clearly showed the individualneedle-like inclusions that one normally expectsfrom a natural star, while the eight-rayed star wasobviously caused by oriented “polish lines” andwas evident only on the surface of the stone (figure10). The close juxtaposition of a natural star to a

Figure 8. The almost-perfect six-rayed star in thistransparent 3.29 ct chrysoberyl was found to bemanufactured. Photomicrograph by Shane F.McClure; magnified 10×.

Figure 9. Natural six-rayed stars in chrysoberyl, asseen in this 2.29 ct cabochon, are very rare. Photoby Maha Tannous.

Figure 7. These photos illustratehow superficial the imitation starsare and that they are being createdby oriented “polishing” lines. Thespecimen on the left may besamarskite; the cabochon on theright is rutile. Photomicrographs byShane F. McClure; magnified 40×.

manufactured one illustrates quite effectively thestriking differences between the two.

It is interesting to note that one of the groups ofsuspect stones we received had a sapphire with a12-rayed star (figure 11). The phenomenon in thisstone was completely natural. For this reason it wasnot included as part of the study group.

Although no one has come forward to say exact-ly how this process is being done, the appearance ofthe stones suggests that it involves the use of a pol-ishing wheel with a coarse grit. The orientedscratches are numerous and packed tightly together,so some type of spinning wheel is probablyinvolved. Also, the asymmetry of most of the speci-mens would suggest that the process is being doneby hand, rather than by some form of automation.

CONCLUSIONThese imitation stars are not difficult to detect inmost cases because of their unnatural appearance.The key, as is often the case in gemology, is inknowing that such a treatment exists, understandingthe sources and appearances of naturally occurring

phenomena such as asterism, and questioning anystone that appears suspicious. Microscopic examina-tion should easily permit the identification, especial-ly with the assistance of a fiber-optic light source.

The presence of a natural 12-rayed star sapphirein one of the groups of suspect stones we receivedserves as a reminder that while stones with such alarge number of rays are rare, they do exist. Onlywith careful microscopic examination can you con-clusively prove the origin of the asterism. Even if astone appears suspicious, you should follow throughwith the proper examination before pronouncingjudgment.

REFERENCES Fryer C., Crowningshield R., Hurwit K., Kane R. (1985) Gem

Trade Lab notes: Corundum. Gems & Gemology, Vol. 21,No. 3, p. 171.

Hurlbut S., Kammerling R. (1991) Gemology, 2nd ed. John Wiley& Sons, New York, 336 pp.

Johnson M.L., Koivula J.I., Eds. (1999) Gem news: Twelve-rayedstar quartz from Sri Lanka. Gems & Gemology, Vol. 35, No.1, pp. 54–55.

Kumaratilake W.L.D.R.A. (1997) Gems of Sri Lanka: A list ofcat’s-eyes and stars. Journal of Gemmology, Vol. 25, No. 7, pp.

453–516.——— (1998) Spinel and garnet star networks: An interesting

asterism in gems from Sri Lanka. Journal of Gemmology, Vol.26, No. 1, pp. 24–28.

Moses T., Reinitz I., McClure S. (1998) Gem Trade Lab notes:Ruby, with a true double star. Gems & Gemology, Vol. 34,No. 3, p. 217.

Webster R. (1994) Gems: Their Sources, Descriptions andIdentification, 5th ed. Revised by P.G. Read, Butterworth-Heinemann, Oxford, England, 1026 pp.


Figure 10. The double star in this 4.28 ct garnet cabo-chon consisted of one natural four-rayed star and onemanufactured eight-rayed star. Note the difference inappearance between the two stars. Photomicrographby Shane F. McClure; magnified 10×.

Figure 11. Natural 12-rayed stars (such as in this4.41 ct sapphire) do exist, but they are easily dis-tinguished from the manufactured stars discussedin this article. Photomicrograph by Shane F.McClure, magnified 10×.

ABOUT THE AUTHORS

Mr. McClure is director of identification services, and Mr.Koivula is chief research gemologist, at the GIA Gem Trade Laboratory in Carlsbad.

ACKNOWLEDGMENTS: The authors wish to thank the fol-lowing for providing the samples for this study: K & K Inter-national of Falls Church, Virginia; Mark Smith of Bangkok,Thailand; and Dudley Blauwet of Louisville, Colorado.

130 GEM TRADE LAB NOTES GEMS & GEMOLOGY SUMMER 2001

DIAMOND“Banded” Twinned CrystalDiamond manufacturers commonlyencounter a wide range of colors andshapes in the crystals they facet.They are routinely required to makequick cutting decisions throughoutthe faceting process. Occasionally,however, a crystal is so unusual thatthe manufacturer stops to ponder it.Such a crystal recently was broughtto the attention of the East Coast lab-oratory by one of our clients.Although the appearance of the crys-tal was intriguing, we were also inter-ested in gaining a better understand-ing of its growth history.

The 14.07 ct elongated diamondcrystal (measuring 21.78 × 7.62 ×7.59 mm) appeared “banded,” withnear-colorless portions on each endand a black area in the middle (figure1). Stepped twin boundaries (twinnedaccording to the spinel law, that is,

with the twin plane parallel to one ofthe octahedron's faces) were found inboth near-colorless portions. The twinplanes, although parallel, were shiftedslightly in position. However, the twonear-colorless portions had differentmorphologies. The portion on the leftin figure 1 had a flattened triangulartwinned morphology with typical re-entrant corners in the boundaries,whereas the near-colorless portion onthe right had a slightly elongated tri-angular shape without clearly visibletwin re-entrant corners. The blackportion was irregular in shape, butroughly spherical, with very roughsurfaces; it had a submetallic luster.The boundaries between the blackcenter and the near-colorless endswere clearly demarcated.

Because the black center sectionappeared so different from the endportions, we thought there mighthave been another material involved.However, the measured specific gravi-ty of the piece was 3.51 (compared to3.52 for diamond), which indicatedthat only diamond was present in sig-nificant amounts. Infrared spectrasuggested that all three parts of thediamond were type Ia, with high lev-els of nitrogen. Raman spectra collect-ed from the three portions confirmedthis result. Several black inclusionswith irregular shapes were observedin the near-colorless portions, butnone of these was located closeenough to the surface of the crystalfor Raman analysis.

Detailed observations at high mag-

nification, using an optical micro-scope (up to 150× ) and a scanningelectron microscope (up to 500× ) atthe California Institute of Technology(Caltech), revealed entirely differentsurface features for the near-colorlessand black portions, which were appar-ently due to a combination of growthand dissolution (figure 2). On the flatsurfaces of the near-colorless portions,the growth features appeared asmacroscopic parallel steps and trian-gular hillocks, particularly in theboundary areas close to the black por-tion. The dissolution features includ-ed tiny etched trigons, with an orien-tation opposite that of the triangularhillocks, and etch figures with rhom-bic forms that followed the symmetryof the structure of the twin boundary.Also, the twin boundaries were slight-ly bent in several places. The roughsurface of the black portion consistedof irregular steps and small crystalliteswith polygonal forms. When exam-ined with strong transmitted light,this portion revealed a rather complexinternal structure, with a near-color-less transparent core and a black rim.

We concluded that this diamondwas a single crystal with a complicat-

EditorsThomas M. Moses, Ilene Reinitz, Shane F. McClure, and Mary L. JohnsonGIA Gem Trade Laboratory

Contributing EditorsG. Robert CrowningshieldGIA Gem Trade Laboratory, East Coast

Karin N. Hurwit, John I. Koivula, and Cheryl Y. WentzellGIA Gem Trade Laboratory, West Coast

Gem Trade LAB NOTES

© 2001 Gemological Institute of America

Gems & Gemology, Vol. 37, No. 2, pp. 130–136

Editor’s note: The initials at the end ofeach item identify the editor(s) or con-tributing editor(s) who provided thatitem. Full names are given for otherGIA Gem Trade Laboratory contributors.

Figure 1. The unusual “banded”structure of this 14.07 ct twinneddiamond crystal is the result of acomplicated growth history.

ed growth history. The black and near-colorless portions represent differentstages and conditions of growth. Thespherical central portion was formedfirst and grew rapidly (as evidenced bythe small crystallites on its surface).The black color is probably due tonumerous tiny and black inclusionslocated mainly on grain boundaries ofthe small diamond crystallites. Thetwo flattened and twinned near-color-less portions then grew from bothsides of the central portion, by meansof a spiral growth mechanism.

Taijin Lu and John M. King

With a Carbonate Inclusion Recently one of the diamond gradersin the West Coast laboratory becamesuspicious of the appearance of a sur-face-reaching inclusion in a 1.43 ctdiamond that could be described as awide feather or a deep, narrow cavity.The grader thought that the crackledtexture observed in the interior of the

inclusion might be due to the pres-ence of some type of artificial filling.When the diamond was brought intothe Gem Identification laboratory, weimmediately noticed that this texturewas very similar to what we had seenin some wide cleavages that had beenartificially filled.

Close examination with 15× mag-nification revealed that where the cav-ity reached the surface, the transpar-ent material in it was slightly under-cut and had a rough texture; it alsocontained numerous highly reflective,nearly parallel compression cracks(figure 3). The width of the cavity atthe surface made it possible to analyzethe filler using the laser Ramanmicrospectrometer. The results wereboth immediate and surprising. Theanalysis showed the undeniable pres-ence of a carbonate in the crack,although an exact match to a specificcarbonate could not be made. To con-firm this visually, we placed a minutedroplet of 10% hydrochloric acid solu-tion on the crack at the surface of thediamond. The resulting effervescentreaction was as expected for a positivecarbonate-HCl acid spot test.

The carbonate calcite has beenidentified previously as an epigeneticinclusion in diamond (that is, itentered the diamond some time afterits formation; see J. W. Harris,“Diamond geology,” in J. E. Field, Ed.,

The Properties of Natural and Syn-thetic Diamond, Academic Press,London, 1992, p. 363). Therefore, thepossibility of a carbonate filling theinterior of a surface-reaching cavity ina diamond is not unheard of. This,however, is the first time we haveidentified a carbonate in a polisheddiamond. Whether or not it would bepossible to use a molten carbonate asa diamond filler is not known,although its susceptibility to attack byacid makes this unlikely. We thereforeconcluded that this was a naturallyoccurring epigenetic inclusion.

JIK and Maha Tannous

With Unusual Mineral InclusionsAn approximately 1 ct near-colorlessround-brilliant-cut diamond recentlysubmitted to the East Coast laborato-ry was found to contain some ratherinteresting inclusions. During theclarity grading process, three tiny(0.05 mm) dark red-brown to blackinclusions, each surrounded by whatappeared to be a brown radiation halo,were observed under the crown (figure4). These inclusions looked rounded

GEM TRADE LAB NOTES GEMS & GEMOLOGY SUMMER 2001 131

Figure 2. The surface features ofthis near-colorless portion (top ofphoto) were very different fromthose of the black portion (bottomof photo) of the diamond crystal.This backscattered-electron SEMimage shows parallel steps, trian-gular growth hillocks, a twinboundary (upper right), and rhom-bic dissolution figures on the col-orless portion, while it alsoreveals the rough surface withirregular steps and small crystal-lites in the black portion.

Figure 3. Numerous subparallel,reflective compression cracks inthe carbonate inclusion in thisdiamond resemble a texturenoted in some fillings in dia-monds. Magnified 15×.

Figure 4. Too deep in the hostdiamond to be analyzed by laserRaman microspectrometry, thesethree tiny (0.05 mm) dark red-brown to black inclusions aresurrounded by what appear to bebrown radiation halos. They arebelieved to be either strontian K-Cr loparite or Cr-chevkinite. Theinclusion seen here through thegirdle of the stone is a reflectionartifact. Magnified 40×.

1.1 mm

132 GEM TRADE LAB NOTES GEMS & GEMOLOGY Spring 2001

or semi-spherical in form, and provedto be too deep within the diamondhost for Raman analysis.

On the basis of visual examinationof similar inclusions in about fiveother diamonds, as well as a searchthrough the literature, we suspectedthat these inclusions were eitherstrontian K-Cr loparite or Cr-chevki-nite. These rather unusual radioactiveinclusions are similar in color to thosefound in this particular diamond,although the latter were too small toprovide a radioactivity reading.Loparite is isometric and chevkinite ismonoclinic. Because the inclusions inthis diamond looked somewhat spher-ical, loparite is perhaps the more prob-able choice (chevkinite tends to formas somewhat elongated, spike-shapedcrystals). Mineral inclusions in dia-monds, however, are often influencedby the diamond structure. Through aprocess known as xenomorphism,even inclusions that are not isometric,such as chrome diopside, can look asif they have an isometric form. Thismeans that chevkinite could not beruled out as a possibility.

Strontian K-Cr loparite and Cr-chevkinite were first discovered asinclusions in diamonds that weretiny fragments (approximately 1.5 ×1.5 mm) from the River Ranch kim-berlite in Zimbabwe. These inclu-sions had a high content of radioac-tive thorium, and contained the high-est amounts of rare-earth andradioactive elements ever reported ininclusions in diamonds; small, brightgreen radiation clouds surroundedeach of the radioactive inclusions.The green color indicated that theclouds had developed at a tempera-ture below 600°C, and had not beenexposed to a temperature higher thanthat since they were formed. The factthat the clouds in the diamond weexamined were brown indicates thatthe stone was heated above 600°C atsome point (in nature or artificially),as illustrated in J. I. Koivula’s Micro-world of Diamonds, Gemworld Inter-national, Northbrook, Illinois, 2000.A good reference for chevkinite andloparite as inclusions in diamond is

M. G. Kopylova et al., “First occur-rence of strontian K-Cr loparite andCr-chevkinite in diamonds,” RussianGeology and Geophysics, Vol. 38,No. 2, Proceedings of the Sixth Inter-national Kimberlite Conference, Vol.2: Diamonds: Characterization, Gen-esis and Exploration, Allerton Press,New York, 1997, pp. 405–420.

JIK and Maha Tannous

FELDSPARWith Chrome Diopside InclusionsThe West Coast lab recently exam-ined an unusual double cabochon thatstandard gemological testing con-firmed to be orthoclase feldspar. The40.14 ct cabochon, which was 22.48mm long (figure 5), was obtained inMogok, Myanmar, by Mark Smith, agemologist and gem dealer inBangkok. The stone contained a num-ber of relatively large green inclu-sions, so that in general appearance itresembled the white plagioclasefeldspars from the Philippines thatcontain deep green uvarovite garnetinclusions. Those feldspars, however,do not show adularescence, whichthis Burmese moonstone did.

Examination with a microscope

revealed that the randomly arranged,transparent-to-translucent greeninclusions were cracked and wellrounded, with no recognizable crystalfaces (figure 6). These features suggest-ed a protogenetic origin for theseinclusions with respect to the feldspar;that is, they formed before their host.Raman analysis established that theinclusions were diopside, and not (asfirst suspected) a species of garnet.EDXRF analysis of the inclusionsdetected the presence of chromium,which is the probable cause of theirgreen color. This is the first exampleof moonstone with chrome diopsideinclusions we have encountered in thelaboratory.

JIK, Maha Tannous,and Sam Muhlmeister

GIBBSITEDyed to Imitate NephriteRecently, the West Coast laboratoryreceived a 10 × 7 × 3.5 mm oval beadfor an identification report. At firstglance, the “spinach” green color ofthe bead (figure 7) appeared to be typi-cal for nephrite jade. However, theoptical properties and structural char-acteristics were quite different fromthose expected for nephrite.

Using a standard gemologicalrefractometer, we obtained a spot

Figure 6. The rounded appear-ance and cracked texture of thechrome diopside inclusions intheir orthoclase host suggestthat the inclusions are protoge-netic. Magnified 5×.

Figure 5. This 40.14 ct doublecabochon from Myanmar is aninteresting mixture of adulares-cent orthoclase feldspar andchrome diopside.

R.I. of 1.58. This reading was too lowfor nephrite jade (which has an aver-age R.I. of 1.61). The specific gravity,determined by the hydrostaticmethod, was approximately 2.09.This figure is also significantly lowerthan nephrite (about 2.95). When weexamined the bead with a gemologi-cal microscope, we observed a densegranular structure; an even col-oration; some small, irregular-shaped, opaque whitish particles;and a few dark brown needle-likeinclusions. The material was verysoft, and was easily scratched with aneedle probe. These properties alsoindicated that the bead had not beenfashioned from nephrite jade.

Next, using a desk-model spectro-scope, we noticed strong absorptionbands at 560, 600, and 650 nm. Thebead fluoresced moderate yellowishgreen to long-wave ultraviolet radia-tion, but was inert to short-wave UV.Since the standard gemological testswere inconclusive, advanced testingwas required to identify this material.With the client’s permission, a minutescraping was taken from an inconspic-uous place (the inside of the drill hole)for X-ray diffraction analysis. The pat-tern obtained matched gibbsite, a clay-like aluminum hydroxide. The mate-rial had been dyed to simulatenephrite jade. This was the first jadeimitation of this type we have seen inthe Gem Trade Laboratory, althoughon a number of occasions we have

encountered dyed gibbsite as a realis-tic imitation for turquoise (see LabNotes: Summer 1983, p.117; Spring1988, p. 52). KNH

Devitrified GLASSResembling JadeAlthough jadeite is one of the morecommon gem materials to be imitat-ed, seldom is the imitation mountedin an ornate setting made with quali-ty craftsmanship. The East Coast labrecently received just such a piece inthe form of a pendant.

The fully backed white metal pen-dant was stamped “18K.” It includednumerous channel-set transparentnear-colorless baguettes, as well assome transparent near-colorless mar-quise brilliants, all bordered by mill-grain detailing. The pendant show-cased a large, thin, semi-transparentto translucent green tablet—carved

with the image of a stork—whichmeasured approximately 33.40 ×40.25 × 1.65 mm (figure 8).

The carved material showed anuneven “patchy” green color through-out, which to the untrained observermight have appeared similar to theaggregate structure of jadeite. Weobtained a spot refractive index of1.60 using a standard gemologicalrefractometer. Patches of the tabletfluoresced a medium chalky yellowto long-wave UV radiation and a veryweak chalky yellow to short-waveUV. Using a standard gemologicalmicroscope (50×) and fiber-optic light-ing, we observed patches of tiny gasbubbles. Higher magnification (200×)revealed a fern-like structure that iscommonly seen in the manufacturedglass known in the trade as "Meta-jade.” The partially devitrified struc-ture confirmed that the carving was amanufactured glass.

Ann-Marie Walkerand Wendi M. Mayerson


Figure 7. This 10×7×3.5 mmbead, which looks like nephritejade, was identified as dyedgibbsite.

Figure 8. The 33.40 ×40.25 ×1.65 mm green carving in this pendantproved to be devitrified glass.

134 GEM TRADE LAB NOTES GEMS & GEMOLOGY Spring 2001

PEARLSEarly Japanese AssembledCultured Blister PearlsThe East Coast lab recently receivedfor identification an intricate whitemetal ring set with three pearls (figure9, left). The setting was stamped“18KT WHITE GOLD” and includednumerous old European- and single-cut stones. The ring had a concavecup setting for each of the three par-tially drilled pearls (figure 9, right),which measured an average of 5.18mm in diameter.

Magnification revealed a nacreousappearance consistent with natural

and cultured pearls. X-radiography,however, suggested that the internalstructure was not typical of the natu-ral or cultured pearls generally seen inthe lab today. Each “pearl” had threecomponents: a layer of nacre, a shellbead with a square notch cut into it,and an oddly shaped mother-of-pearlbacking cut to fit into the squarenotch (figure 10). Most unusual wasthe fact that the mother-of-pearl back-ing was rounded on the bottom togive the overall appearance of a fullyround pearl. We therefore concludedthat these were assembled culturedblister pearls.

We have previously reported onsimilar cultured pearls in the LabNotes section (Summer 1983, p. 116;Spring 1988, pp. 49–50; Spring 1994,pp. 44–45). They were produced inJapan prior to the successful culturingof solid round pearls. Although thelab has not seen very many of them,we know that Kokichi Mikimoto wasmarketing assembled cultured blisterpearls as early as 1890, with produc-tion exceeding 50,000 annually.

While one might at first assumethat these assembled cultured blisterpearls were set in the ring to replacelost or worn natural pearls, the factthat they probably represent earlyMikimoto production makes it morelikely that they were original to the

ring itself. In addition, they fit pre-cisely into the cupped backs, anoth-er indication that they were originalto the ring. Knowledge of their his-tory can aid in dating this piece ofestate jewelry.

Ann-Marie Walker and Wendi M. Mayerson

Faceted Cultured Pearls, Dyed BlackAn 8 mm black faceted pearl was sentto our West Coast laboratory for anidentification report. The client hadnoticed unusual “color spots” thatmade him question whether it wasindeed a natural-color Tahitian cul-tured pearl. Although we cannotdetermine a pearl’s provenance, wecan determine its identity, whether itis natural or cultured, and whether ornot it has been treated.

The item had an attractive blackbodycolor and showed strong purplishpink overtones (figure 11). Most of thepolygonal facets had been well placedand polished, leaving the surface witha smooth finish. X-radiography re-vealed a fairly large bead nucleus,which confirmed that this was a cul-tured pearl. Using 10× magnificationwith strong overhead illumination,we observed that the nacre was actu-ally dark brown. This color wasunevenly distributed, and concentra-tions in some areas gave the surface aslightly spotted appearance. Magnifi-cation also revealed that some facetshad been damaged extensively duringfashioning. Fairly deep grooves (somestraight and others circular) werenoticeable. On some facets the topnacre layer had been removed, expos-ing an almost colorless layer of nacre(figure 12). Along the rims of thoseexposed areas was an opaque, lightbrown deposit of unknown identity.

The reaction to long-wave UVradiation was quite peculiar. Theexposed near-colorless nacre layer flu-oresced chalky yellowish white, simi-lar in appearance to natural-colorlight nacre shell layers. The blacknacre surface, however, did not show

Figure 10. This X-radiographreveals the unusual assemblageof the cultured blister pearlsshown in figure 9.

Figure 9. Assembled cultured blister pearls such as the ones in this ring(left) were first produced by Kokichi Mikimoto in 1890. Note on theback the concave cups into which they fit precisely (right).

any fluorescence. Natural-color blacknacre fluoresces either reddish brownor red to long-wave UV. The absenceof this type of fluorescence in the topnacre layer proved that it had beentreated. EDXRF chemical analysisrevealed the presence of silver, which

further substantiated our conclusionthat the cultured pearl had been treat-ed to attain its black color. As to thecause and nature of the brown depositaround the rims of exposed areas, wecould only speculate that it was abyproduct of the faceting and treat-ment process. KNH

A New Imitation: “Shell Pearls”with a Calcite BeadThis year in Tucson, we purchased astrand of 34 imitation “baroque”pearls (12.50–11.60 mm × 10.30–9.75mm; figure 13), which were sold as“shell pearls” by Tiger Trading, FreshMeadows, New York, at the GJXShow. These imitation pearls wereoffered in rounds ranging from 8 to 14mm, as well as in “baroque” shapessuch as those in the strand we pur-chased. They came in a variety of col-ors. Besides the “Tahitian” colorscheme of our strand, “South Sea”and standard “akoya” colors wereavailable. The seller reported thatthey were mother-of-pearl beads—asare sometimes used in imitationpearls—that had been coated to looklike many different types of pearls.

The regularity of shape of the“baroque pearls” and the multiplelayers visible at the drill holes (figure14) seemed to support the seller’sdescription. However, a close inspec-tion in reflected light also revealedwhat appeared to be facets under thecoating. Given the unusual shape anduniformity of these “pearls,” we werecurious to learn whether their cen-ters were in fact shell.

To examine the core material, wedecided to sacrifice one of the


Figure 14. The view down thedrill hole readily revealed thatthis imitation pearl had multi-ple layers of some type of coat-ing. Magnified 50×.

Figure 13. This strand of 34 “baroque” imitation pearls was sold as“shell pearls.”

Figure 12. With magnification(here, 15×) a second, almost col-orless, nacre layer wasrevealed, and a light browndeposit was seen where the topnacre layer had been removedduring fashioning.

Figure 11. This 8 mm blackfaceted cultured pearl revealedevidence of treatment. Note thedifferent color of the lower nacrelayer that was exposed on somefacets during fashioning.

imitation pearls in the strand. Using aprocedure we normally would notperform, we immersed a light gray“shell pearl” in acetone (standard nailpolish remover) in an attempt tobreak down the coating and exposethe bead. After 30 minutes, the coat-ing was soft enough to be squeezedwith tweezers. In fact, the coating fitloosely, like a plastic bag around ahard center. When the object wassqueezed with tweezers, a dark cloudor “puff” was exuded through thedrill hole into the nail polish remover.More squeezing ruptured the coatingand released the bead nucleus.

As can be seen in figure 15, thecoating was quite thick and consistedof two different types of layers—trans-parent colorless external layers andopaque metallic light gray internallayers. It was part of the internal col-ored material that, because it was inthe process of dissolving, had squirtedout of the drill hole when the assem-blage was squeezed in acetone.

The bead was translucent whiteand banded (again, see figure 15). Thespot reading, taken with a standardrefractometer, revealed a carbonateblink from 1.48 to 1.65, and thepolariscope established that the

material was a crystalline aggregate.On the basis of these findings and aspecific gravity of 2.75, we identifiedthe bead as calcite, rather than moth-er-of-pearl. Although both materialsconsist mainly of CaCO3, mother-of-pearl—a shell material—containsorganic matter and water in its struc-ture as a result of being excreted by aliving creature. It should be notedthat shell beads, not calcite, are thestandard nucleus for cultured pearlsin the industry today. A strand ofvery similar appearing pearls wasrecently advertised for sale as “moth-er of pearl jewelry” in the catalogueof a major department store. A spe-cial note stated that “Mother of pearljewelry is derived from the inner lin-ing of an oyster shell. This collec-tion’s magnificent luster is enhancedby a man-made protective coating.Again, we say caveat emptor—“buyer beware.”

Wendi M. Mayerson

136 GEM TRADE LAB NOTES GEMS & GEMOLOGY SUMMER 2001

Figure 15. The coating removed from the imitation "shell" pearl wasfound to consist of two types of layers (left): external transparent color-less layers and internal opaque light gray metallic layers. Gemologicaltesting identified the bead nucleus (right) as calcite.

PHOTO CREDITSMaha Tannous—figures 1, 5, 7, 11, and 12;Taijin Lu—figure 2; John I. Koivula—figures3, 4, and 6; Jennifer Vaccaro—figures 8and 13; Elizabeth Schrader—figures 9 and15; Ann-Marie Walker—figure 10; WendiMayerson—figure 14.

The Treasured Gifts Council, chaired by Richard Greenwood, was established to encourage individualand corporate gifts-in-kind of stones, library materials, and other non-cash assets that can be used directly in GIA s educational and research activities. Gifts-in-kind help GIA serve the gem and jewelryindustry worldwide while offering donors significant philanthropic and tax benefits. We extend a sin-cere thank you to all those who contributed to the Treasured Gifts Council in 2000.

Thank You,Donors

In its efforts to serve the gem and jewelry industry, GIA can use a wide variety of gifts. These include natural untreated andtreated stones, as well as synthetics and simulants, media resources for the Richard T. Liddicoat Library, and equipment andinstruments for ongoing research support. If you are interested in making a donation, and receiving tax deduction information,please call Heather Childers at (800) 421-7250, ext. 4139. From outside the U.S. call (760) 603-4139, fax (760) 603-4199.Every effort has been made to avoid errors in this listing. If we have accidentally omitted or misprinted your name, pleasenotify us at one of the above numbers.

$100,000 or HigherDaniel & Bo Banks

$10,000 to $49,999Robert & Marlene AndersonHarry G. Kazanjian & Sons, Inc.Kennecott ExplorationCompanyWilliam and Jeanne LarsonOro AmericaFrederick H. Pough, Ph.D.John & Laura RamseyKen RobertsMarc SarosiLeo F. Stornelli, M.D.

$5,000 to $9,999Theodore & Corinne GrussingScott D. Isslieb, G.G.Christopher LaVarcoElena Villa HamannWorld Sapphire

$2,500 to $4,999Lee AllisonArgyle DiamondsRichard E. BrownCapalion EnterprisesMartin B. de Silva, G.G.Ebert & CompanyInland Empire Alumni ChapterIsland Legacy, Ltd.

Jewelmer International Corporation

Leo Hamel & CompanyDonald K. Olson & AssociatesTycoonJim Yaras

$1,000 to $2,499 Associated Gem & Jewelry

Appraisal ServiceHeitor Dimas BarbosaGary W. Bowersox, G.G.Douglas BurleighEsther FortunoffGIA ResearchBen Gordon, G.G.Barbara HessJohannes Hunter JewelersLinda KoenigWilliam C. ReimanSara Gem CorporationSirimitr Mining Co., Ltd.Velma Touraine

$500 to $999 Allerton Cushman & Co.Irv BrownEquatorian Imports, Inc.Erbgem CompanyBrian Hudson

Kwiat, Inc.Raul Haas/Hyde Park JewelersJ. Blue SheppardSherry Stuckey

Under $500 Ronnie AlkalayAmerican Deepwater

EngineeringBeija-Flor GemsK. C. BellWilliam E. Boyajian, G.G.Ann D. BroussardCarl Chilstrom, G.G.Donald ClaryProfessor Jório CoelhoJo Ellen Cole, G.G., F.G.A.Companhia Baiana de Pesquisa MineralStevie DillonDona M. Dirlam, G.G., F.G.A.Pete J. Dunn, Ph.D.David S. EpsteinElaine Ferrari-Santhon, G.G.,

C.G.Sondra Francis, G.G.Gebrüder Bank GemstonesMaggi R. GunnBarbara E. Haner

Hearts On Fire CompanyClaus Hedegaard, Ph.D.Herteen & StockerJan David Design GoldsmithA. J. A. Janse, Ph.D.Jewelry by Gail, Inc.Mary L. Johnson, Ph.D.Jonté Berlon GemsJoseph's JewelersRobert E. Kane, G.G.Joachim Karfunkel, Ph.D.Gail Brett Levine, G.G.Veston MalangoWendi M. Mayerson, G.G.Yves MorrierPrimary Industries & Resources

SADwight Rodrigues SoaresDouglas RountreeJackie RussellScheherazade JewelersArt SexauerThorsten A. Strom, G.G.Topázio ImperialPaige S. Tullos, G.G.United States Pearl Co., Ltd.Martha M. Wampler, G.G.Betty WaznisVictor E. Zagorsky, Ph.D.

THANK YOU, DONORS GEMS & GEMOLOGY SUMMER 2001 137

138 GEM NEWS INTERNATIONAL GEMS & GEMOLOGY SUMMER 2001

EDITORBrendan M. Laurs ([email protected])

CONTRIBUTING EDITORSEmmanuel Fritsch, IMN, University of Nantes, France ([email protected])

Henry A. Hänni, SSEF, Basel, Switzerland([email protected])

Kenneth Scarratt, AGTA Gemological Testing Center,New York ([email protected])

Karl Schmetzer, Petershausen, Germany

James E. Shigley, GIA Research,Carlsbad, California ([email protected])

Christopher P. Smith, Gübelin Gem Lab,Lucerne, Switzerland ([email protected])

GEM NEWS International

DIAMONDS Royal Asscher cut. Amsterdam’s Royal Asscher DiamondCo., cutters of the Cullinan diamond, recently debutedthe Royal Asscher cut (figure 1) at the JCK show in LasVegas. The original Asscher cut (patented in 1902) was asquarish diamond with large corners, a high crown, asmall table, and a deep pavilion (see, e.g., p. 165 of the Fall1999 issue of Gems & Gemology). With 74 facets and amore geometric look, the Royal Asscher still retains thedistinctive appearance of its predecessor. Both loosestones and a Royal Asscher cut diamond jewelry line arebeing marketed through M. Fabrikant & Sons, New York.Each diamond is accompanied by a GIA Gem TradeLaboratory diamond certificate.

Diamonds in Canada: An update. In 1991, Canada’sNorthwest Territories (NWT) was catapulted into theworld spotlight with the discovery of diamond-bearingkimberlites in the Lac de Gras area of the SlaveGeological Province (see, e.g., A. A. Levinson et al.,“Diamond sources and production: Past, present, andfuture,” Winter 1992 Gems & Gemology, pp. 234–254).Success has been swift, with several major developmentsin the last 10 years. The Ekati mine started production in1998 (see, e.g., Winter 1998 Gem News, pp. 290–292), andthe Diavik project is scheduled to begin production in2003 (see the following entry by K. A. Mychaluk on afield excursion to these two mines). The Jericho and SnapLake projects are in the “permitting” stage, with antici-pated production slated to begin in 2003 and 2004, respec-tively. At least 250 additional occurrences of kimberlite,many of which are diamond bearing, have been discov-ered in the Slave Geological Province.

Three cutting factories (Sirius, Deton’Cho, andArslanian) are operating in Yellowknife (the capital of theNWT). These factories provide training and employmentfor aboriginal people, as they supply the world marketwith Canadian mined, cut, and polished diamonds.Several brands of Canadian diamonds are now availablewith laser-inscribed logos (e.g., polar bear, snowflake, andmaple leaf); in April 2001, BHP Diamonds, operator of theEkati mine, began marketing EKATI™ diamonds.

The discovery of diamonds in the NWT led to accelerat-ed exploration activity elsewhere in Canada as well.Currently, exploration is fueled primarily by the efforts ofthree major mining companies (De Beers Canada Mining,BHP Diamonds, and Rio Tinto) and about 30 smaller, juniorto mid-sized companies. In recent years, numerous kimber-lites have been found in western Canada (i.e., northernAlberta—44 pipes in two separate areas, discovered since1996; and Saskatchewan—71 kimberlites, found primarilyin the Fort à la Corne area since 1988). Encouraging resultsfrom surveys of diamond indicator minerals in Manitoba

Figure 1. Updating a traditional look, the Royal Asschercut (here, 6.35 ct), debuted at the June 2001 JCK show inLas Vegas. Courtesy of M. Fabrikant & Sons.

GEM NEWS INTERNATIONAL GEMS & GEMOLOGY SUMMER 2001 139

glacial tills have generated exploration activity there, but nodiamond-bearing kimberlite has yet been found.

In central and eastern Canada, most exploration activ-ity is taking place in two areas of Ontario: Wawa and theJames Bay Lowlands (JBL; part of which is also inQuebec); the potential for diamonds in the JBL was firstsuggested a century ago (again, see Levinson et al., 1992).The large (16.7 ha) Victor pipe in the Attawapiskat area ofthe JBL is the most advanced Canadian diamond projectoutside the NWT, and is currently being evaluated by DeBeers Canada Mining. Diamond exploration is gainingmomentum in Quebec, primarily in three widely separat-ed areas: the JBL, the Otish Mountains, and Torngat. Inthe Torngat area of the Ungava Peninsula (northeasternQuebec), at least 60 dikes of kimberlitic affinity, up to 5m thick, can be traced for up to 10 km; although manycontain diamonds, thus far these are uneconomic.

In 2000, the Ekati mine produced about 2.6 millioncarats of rough with an average value of nearlyUS$170/ct; this represents approximately 2.5% of worldproduction by weight and 5% by value. By 2005, if theDiavik, Jericho, and Snap Lake mines are in full produc-tion, Canada’s contribution to the world supply of roughdiamonds could be approximately 10% by weight and15% by value. Yet, the exploration component of theCanadian diamond industry is still at an early stage, ascompared to major producing countries (e.g., Botswana,South Africa, and Russia). The importance of the fledglingCanadian diamond industry apparently has not escapedthe notice of unsavory (even criminal) elements. As earlyas May 1999, a mere six months after the opening of theEkati mine, polished diamonds purported to beCanadian—but in far greater abundance than could con-ceivably have been mined and polished in that timeframe—were being offered for sale on the world market(see, e.g., B. Avery, “That Canadian diamond may bebogus,” Calgary Herald, May 15, 1999, p. D11). Morerecently, and of far greater concern, it has been suggestedthat “conflict” diamonds have been smuggled intoCanada to circumvent international embargos (see, e.g.,A. Mitrovica, “Smuggled ‘blood’ diamonds are here,police fear,” Globe and Mail, March 29, 2001, p. A1).

Alfred A. LevinsonUniversity of Calgary, Calgary

[email protected]

Bruce A. KjarsgaardGeological Survey of Canada, Ottawa

Field excursion to Canadian diamond mines. The dia-mond deposits of Canada’s Northwest Territories (NWT)were recently highlighted at the 37th Forum on theGeology of Industrial Minerals, held in Victoria, BritishColumbia on May 22–25. This contributor participated ina four-day post-meeting field trip to the NWT, led by Dr.George Simandl of the British Columbia Ministry of

Energy and Mines. The itinerary included visits to theEkati mine (operated by BHP Diamonds), the Diavik pro-ject (a joint venture between Diavik Diamond Mines andAber Diamond Corp.), the Snap Lake project (owned byDe Beers Canada Mining) and a diamond cutting facilityoperated by Sirius Diamonds in Yellowknife (for loca-tions, see map accompanying D. Paget’s “Canadian dia-mond production: A government perspective,” Fall 1999Gems & Gemology, pp. 40–41).

Darren Dyck, senior project geologist for BHPDiamonds, was our host at Ekati. We toured the mine,processing plant, tailings containment area, and livingquarters for the mine’s 400 personnel. The mine is cur-rently extracting ore only from the Panda pit; eventually, atotal of five kimberlites will be exploited (see Winter 1998Gem News, pp. 290–292). The Panda pit, now at half itsprojected open-pit depth of 300 m, is 500 m in diameter atthe top (see figure 2). Large amounts of granitic country

Figure 2. The Panda pit at the Ekati mine, currently150 m deep, is now at half its projected open-pitdepth of 300 m. The predominant rocks in thephoto are granitic country rocks that surround thediamond-bearing kimberlite (not visible). The rect-angular area in the lower left corner of the pit hasbeen drilled in preparation for blasting. The oretrucks are designed to haul 240 tons of rock. Phototaken on May 27, 2001, by K. A. Mychaluk.

Editorís note: Bylines are provided for contributing editorsand outside contributors; items without bylines were pre-pared by the section editor or other G&G staff. All contribu-tions should be sent to Brendan Laurs at [email protected] (e-mail), 760-603-4595 (fax), or GIA, 5345 Armada Drive,Carlsbad, CA 92008.

GEMS & GEMOLOGY, Vol. 37, No. 1, pp. 138–159© 2001 Gemological Institute of America

rock must be removed to mine the kimberlite; the strip-ping ratio is 14:1 (14 tonnes of granite for each tonne ofkimberlite). Excavation of the pit has also exposed a small-er kimberlite pipe and several kimberlitic dikes. Eocene-age fossils have been recovered from crater-facies kimber-lite in the Panda pit, including Metasequoia logs, fishteeth and scales, and a turtle femur; these suggest that thePanda kimberlite erupted 50 million years ago. Pre-strip-ping of two of the other four pipes, the Misery and theKoala, has already begun, with production expected tostart in mid-2001 and spring 2002, respectively.

Currently, 10,000 tonnes of Ekati kimberlite are pro-cessed each day. After initial crushing and screening,about 4,000 tonnes/day undergo heavy-media separation.The resulting 200 tonnes/day of concentrate are processedby X-ray sorting (a small amount is also sent to a greasetable). Security protocols prevented our visiting the X-raysorting facility; in fact, security was tight throughout thetour. Using data gathered through a continuous series ofaudits, BHP Diamonds believes that they are recovering99.9% of the diamonds larger than 1 mm (diamonds small-er than 1 mm are rejected into the tailings). A display ofrough diamonds, typical of a day’s production, was shownto our group. These stones, which would fill a coffee can,consisted primarily of sharp, near-colorless octahedronsand macles.

We saw evidence of many safety and environmentalprotection measures at Ekati. The most impressive wasthe Panda Diversion Channel, a >3-km-long canal thatdiverted water and fish from Panda Lake (which coveredpart of the Panda kimberlite) to Kodiak Lake. As part ofthe effort to minimize the environmental impact of min-ing the Panda pit, the canal reportedly channeled over3,000 fish to Kodiak Lake last year.

At the Diavik project, more than 850 employees (anumber that was expected to grow to 1,100 this summer)are constructing Canada’s second diamond mine, which isprojected to begin production in 2003. Arnold Enge, publicaffairs officer for Diavik Diamond Mines, navigated ourgroup through the very busy site. The mine will extractore from four Eocene-age kimberlite pipes (A-154S, A-154N, A-418, and A-21) under the shallow waters of Lac deGras, via three open pits. Construction has begun on theprocessing plant (figure 3), living quarters, a myriad ofroads, and the first of several dikes designed to hold backthe waters of Lac de Gras. An estimated 8.9 million m3 ofrock will be used in dike construction, and 26.5 millionm3 of water will be pumped out before mining can begin.Over this past winter, 4,089 truckloads of materials,including 44 million liters of diesel fuel, were transportedto the site on a 425 km “ice road” that connects Diavikwith Yellowknife during the winter months.

Our hosts at the Snap Lake project were geologistMike Allen and assistant site manager Jack Haynes, bothof De Beers Canada Mining. Highlights included anunderground tour of the diamondiferous kimberlite dike,which dips 5°–15° east under Snap Lake. A tunnel fromwhich a bulk sample of the dike is being extracted hasadvanced 1,250 m along dip, and there are 600 m of addi-tional workings along strike of the dike. On the basis ofits composition and texture, the dike is believed to con-sist of a single intrusion of spinel-bearing phlogopite-monticellite kimberlite. It has been dated at 523 millionyears old, which is much older than the kimberlites atEkati and Diavik. In 2000, approximately 6,000 tonnes ofkimberlite from the tunnel were processed for ore-gradeestimation. Future development will include severalactivities: extending the decline (500 m along dip and 400m along strike), processing 9,000 tonnes of kimberlite,auditing the tailings, conducting an experimental seismicsurvey (with Diamondex Resources Ltd. and theUniversity of British Columbia), implementing a fishhabitat compensation program, and performing environ-mental baseline studies. Commercial diamond produc-tion is slated for 2004.

In Yellowknife, Jennifer Burgess, diamond resourcespecialist with Diavik Diamond Mines, gave us a techni-cal presentation on the geology of the Diavik project. Adrill core (from A-154S) and rough diamonds from theproject were made available for microscopic examina-tion. The core samples clearly showed the layered vol-caniclastic nature of the Diavik kimberlites. Each kim-berlite pipe at Diavik contains several volcaniclasticunits with different ore grades. Diamondiferous nodulesof eclogite (garnet lherzolite) have been found in theDiavik kimberlites, and both eclogitic and peridotiticdiamonds have been identified.

Ten percent of Ekati’s production is sold toYellowknife-based cutting operations. Our tour of theSirius Diamonds facility in Yellowknife was led by man-ager Peter Finnemore. About twenty cutters (see, e.g., fig-


Figure 3. At the future Diavik diamond mine, a kim-berlite processing plant is being constructed. Thetower in the left center of the photo will be theexhaust stack for the processing plant, and the low,white buildings in the distance are temporary livingquarters for 700 people. The four kimberlite pipes thatwill be mined are located under the shallow waters ofthe ice-covered Lac de Gras in the far distance. Phototaken on May 28, 2001, by K. A. Mychaluk.

ure 4) facet about 500–600 carats of rough (with finishedweight averaging 50 points each) per month (average colorG or better). With less than two years in operation, Siriushas faced high labor costs and a 50% turnover among itscutters. As such, the talent base for cutting fancies is notyet available, according to Mr. Finnemore. Currently,80% of Sirius’s sales are domestic. Mr. Finnemore statedthat two other Yellowknife-based cutting facilities,Arslanian and Deton’Cho Diamond, employ approxi-mately 55 and 25 cutters, respectively. A diamond-sortingfacility in Yellowknife, owned and operated by BHPDiamonds, employs about a dozen people.

Keith A. MychalukCalgary, Alberta, Canada

Diamond presentations at the PDAC conference. With anattendance of nearly 7,000, this year’s annual conferenceof the Prospectors and Developers Association of Canadawas held March 11–14 in Toronto. The main focus wasexploration for diamonds and platinum group metals. Theatmosphere was reminiscent of the diamond rush in theearly 1990s, when scores of junior exploration companiespromoted their properties (though only a few ultimatelyreached production status). Aside from the usual updateson specific projects, this year’s diamond presentationsincluded several market forecasts aimed at the investor,as well as projections about future demand.

De Beers’s Gary Ralfe gave a lunchtime address inwhich he outlined the company’s future role, specificallyits transition from being a custodian of the diamondindustry by controlling the availability of rough, tobecoming the “supplier of choice.” In the more formalpresentations, Matt Manson of Aber Diamond Corp.observed that there is now pressure to shorten the dia-mond pipeline from both ends—retailer as well as produc-er—through tighter relationships and amalgamations. Headded that with brand names, hallmarks, and e-commercegaining widespread acceptance, the long-term outlookremains bright. Aber’s Bob Gannicott examined prefer-ences among buyers in the U.S., Southeast Asia, andJapan for diamond color, size, and clarity. He observedthat Canadian diamonds show an unusually good fit tothe demands of the American market, where the “babyboomer” generation (now 45–55 years old) has more dis-posable income to spend on luxury goods.

Malcolm Thurston of MRDI USA discussed howinvestors can evaluate information on diamond projects,from prospect to feasibility. He introduced the “four Q’s”:quality of data, quality of geologic modeling, quality ofore and cost estimates, and quantity of risk. All data mustbe collected and interpreted under a well-designed, prop-erly supervised program of quality assurance and control.Dr. Johan Ferreira of De Beers downplayed the signifi-cance of micro- and macro-diamond size distribution indiamond resource estimation. He maintained thatalthough the relationship is real, many other factors such

as sample site, volume, recovery method, and analysis ofshapes and sizes must be considered. Dr. Larry Heaman ofthe University of Alberta noted the wide range in the agesof kimberlite emplacement, in some instances for pipesseparated by short distances (as in the Slave GeologicalProvince of Canada’s Northwest Territories [NWT]).Episodes of kimberlite/lamproite emplacement that arecurrently known to be most economic are Precambrian(e.g., Premier pipe, South Africa; Argyle pipe, Australia),Devonian (Republic of Sakha, Russia), Cretaceous (SouthAfrica), and Tertiary (NWT, Canada). John McConnell ofDe Beers Canada Mining presented the latest results onthe Snap Lake project, which may become Canada’s thirddiamond mine.

In the less formal Exchange Forum presentations, thedirectors of several junior exploration companies briefedattendees on the latest developments in Africa, Canada,and elsewhere. The projects discussed included: alluvialdiamonds and potential pipe targets in South Africa, off-shore operations near Lüderitz in Namibia, alluvial opera-tions along the lower Orange River at Baken and the mid-dle Orange River near Douglas (both in South Africa), dis-coveries in western Liberia’s Mano River kimberlite field,the Aylmer West property in Canada’s NWT, the latestkimberlite discovery in the Fort à la Corne kimberlitefield in Saskatchewan, kimberlite and diamond discover-ies in the Buffalo Hills area of Alberta, an update on theNWT’s Jericho kimberlite, and the possibility of kimber-lite pipes at the NWT’s Snap Lake (in addition to theproven diamondiferous dike). Also presented were theresults of exploration in Brazil and in the Wawa andJames Bay Lowland areas of Ontario, Canada; the evalua-


Figure 4. Shane Fox, one of about 20 cutters presentlyworking at the Sirius Diamonds factory inYellowknife, is shown faceting a round brilliant. Thecompany currently cuts 500–600 carats of rough Ekatidiamonds per month. Photo by K. A. Mychaluk.

tion of the Payalikand kimberlite pipe in the new state ofChhattisgarh in India; and the problems of estimating theaverage value per carat in mine evaluation studies.

Overall, the mood of the conference was optimistic,with the number of diamond exploration projects increas-ing as venture capital is forthcoming once again.

A. J. A. (Bram) JanseArchon Exploration, Carine, Western Australia

[email protected]

A table with trigons. Diamond crystals commonly displaytriangular growth features on their surface, called trigons.After faceting, such features may be preserved on tinyrelict crystal faces (“naturals”) along the girdle or, lesscommonly, elsewhere on the diamond. It was with greatsurprise, therefore, when Richard Cloutier (GemteckAppraisal Service, Phoenix, Arizona) observed trigons cov-ering the table of a faceted diamond.

Mr. Cloutier was appraising an antique 18K yellowgold pin set with 13 diamonds when he noticed trigons onthe table of one of the stones during his preliminary exam-ination with a 10× loupe. Examination of the 2.4-mm-diameter diamond with a microscope revealed trigons overthe entire surface of the table (figure 5). Perhaps an unusu-al shape to the rough caused the cutter to use the trigon-containing octahedral face for the table.

COLORED STONES ANDORGANIC MATERIALSAmber (“Burmite”) from Myanmar: Production resumes.Amber from Myanmar (Burma) has been used by Chinesecraftsmen to produce art objects since the 1st century AD(see V. V. Zherikhin and A. J. Ross, “A review of the histo-ry, geology and age of Burmese amber [Burmite],” Bulletinof the Natural History Museum [London], Geology Series,Vol. 56, No. 1, 2000, pp. 3–10). However, it rarely reachedWestern markets before the late 19th century. The depositsare located in the Hukawng Valley, northern Kachin State,about 80 km north-northeast of the famous jadeite miningarea in the Uru River valley (U Tin Hlaing, “Burmite—Burmese amber,” Australian Gemmologist, Vol. 20, No. 6,1999, pp. 250 –253). The amber, sometimes called“Burmite,” shows many differences from material derivedfrom the Baltic and the Dominican Republic. Specifically,it ranges from almost perfectly transparent to opaque, hasmore-saturated and darker colors (which vary from yellowto red, with dark reddish brown being typical), and, withrespect to the Baltic material, is reported to have greaterhardness and density (R. Webster, Gems, 5th ed., revised byP. G. Read, Butterworth-Heinemann, 1994, p. 573). The lasttwo characteristics make Burmite particularly amenable tocarving and manufacture into jewelry (figure 6).

Prior to World War II, while the country was still underBritish rule, commercial quantities of Burmese amber wereproduced. Since the 1940s, however, the material has beenessentially unavailable due to internal problems. Miningresumed in the mid-1990s, and from 1995 to 1997 severalcommercial shipments of Burmite were made to China.Since then, for various reasons including low prices for theamber, there has been little formal mining and essentiallyno export of either rough or polished material.

Recently, however, a new joint venture has begun toexploit the material, with the goal of exporting 500 kg(1,100 pounds) of Burmite annually during the next fewyears. In 2000, Leeward Capital Corp., a Calgary-basedCanadian company, made a contractual arrangementwith a Myanmar company to purchase all the Burmiteproduced in the mining area located near the town ofTanai along the Ledo Road (of World War II fame). Usingsimple recovery methods (figure 7), as many as 60 minerswork the deposits during the dry season. First they digtest pits to locate an unweathered amber-containingseam, and then they use open-pit methods to mine this


Figure 5. The table of this 2.4-mm-diameter dia-mond is covered with trigons. Photomicrograph byRobert Cloutier.

Figure 6. Swirls of color are commonly seen inpolished Burmite from the Hukawng Valley,Myanmar. The earring pendants each measure2.1 × 3.0 cm. Photo by Maha Tannous.

horizon. Most of the amber is found as disc-shaped frag-ments that range from a few millimeters up to severalcentimeters in diameter. Large-scale mechanized miningis not feasible, because the material is too delicate andthe seams are too narrow. In 2000, Leeward Capitalobtained 78 kg of Burmite, and by June 2001 a total of300 kg of mixed-grade material had been obtained inpieces up to 25 cm in maximum dimension.

Inclusions of insects and other biological materials(e.g., pollen and plant remains) appear to be more abun-dant in Burmite than they are in Baltic amber (J. W. Davis,pers. comm., 2001; see also abstract of “The history, geol-ogy, age, and fauna [mainly insects] of Burmese amber,Myanmar” in the Gemological Abstracts section). So far,inclusions have been found in an average of 30 pieces perkilogram of current production. The entombed insects

(see, e.g., figure 8) indicate a Cretaceous age of ~100 mil-lion years (Dr. D. A. Grimaldi, pers. comm., 2001), whichis significantly older than amber from the DominicanRepublic (~30 My) or the Baltic (~40 My; see, e.g., D. A.Grimaldi, Amber: Window to the Past, Harry N. Abrams,New York, 1996).

Alfred A. Levinson

Cat’s-eye amethyst from Brazil. Amethyst is one of themore common gems, but it rarely displays chatoyancy.Therefore, this contributor was most intrigued by twocat’s-eye amethysts he purchased during a visit to Brazilin summer 2000.

The translucent, dark violet stones weighed 30.91 and19.39 ct (figure 9). With standard gemological testing,they both had a spot R.I. of 1.55 and a specific gravity of2.65. When examined with a polariscope, both stonesshowed normal extinction (whereas purple chalcedonywould have exhibited an aggregate structure). With mag-nification, the amethysts revealed distinct color zoning,as well as a dense array of fibrous inclusions oriented per-pendicular to the color zones (figure 10). These inclusionswere distributed homogenously in both stones, and wereresponsible for their chatoyancy.

With high magnification, the fibrous inclusionsappeared to consist of tiny elongate negative crystals andtwo-phase inclusions. They also were visible in two otherorientations, at an angle of approximately 45° to the maindirection. Their exact crystallographic orientations couldnot be measured, because the translucency of the stones


Figure 7. Miners follow the dark-colored amber-bearing horizon in search of Burmite at the NoijeBum mine, near Tanai, Kachin State, Myanmar.The open-pit area at this mine measures 30 × 120 m.Photo by R. D. Cruickshank.

Figure 9. This 19.39 ct amethyst from Brazil dis-plays chatoyancy. Photo by Jaroslav Hyrsl.

Figure 8. This 1 mm parasitic wasp (Serphitidae) inBurmite is characteristic of the Cretaceous Period,and provides evidence that the amber is about 100million years old. Photo © Dr. D. A. Grimaldi,American Museum of Natural History, New York.

hindered determination of the optic-axis direction.Although present in both stones, fibrous inclusions withthese suborientations were more common in the largersample. Therefore, the smaller amethyst showed morepronounced chatoyancy.

Jaroslav Hyrsl Kolin, Czech Republic

[email protected]

Brownish red to orange gems from Afghanistan/Pakistanmisrepresented as bastnäsite and other materials. Duringthe 2001 Tucson show, one of us (DB) received from thecutting factory a number of faceted brownish red toorange stones that were reportedly bastnäsite. The roughwas purchased in Peshawar, Pakistan, and the locationwas given as a tribal area on the Pakistan/Afghanistanborder northwest of Peshawar. Examination of severalstones by JH revealed that one of them was actuallygrossular garnet.

Also at the 2001 Tucson show, one of us (JH) pur-chased two brownish orange stones that were representedas sphene from Afghanistan or Pakistan. Gemologicaltesting showed that one of the stones was indeed sphene,but the other was zircon. Subsequent gem testing of five“bastnäsites” from DB revealed that one of them also wasa sphene. DB also submitted a brownish yellow-orangegemstone to the GIA Gem Trade Laboratory in Carlsbad,which was subsequently identified as sphene (figure 11).Clearly, these four red-to-orange gem materials are easilymisidentified by the miners and dealers. Identification ofthe rough is especially difficult because it is typically bro-ken and weathered.

It is easy to separate grossular from the other gems byits isotropic optic character. The doubly refractive gemsmay show distinctive features with the spectroscope:Zircon has a distinctive spectrum, bastnäsite shows many

strong lines due to rare-earth elements (see Summer 1999Lab Notes, pp. 136–137), and sphene has a faint “didymi-um” spectrum that is identical to that of yellow apatite(see, e.g., R. Webster, Gems, 5th ed., revised by P. G. Read,Butterworth-Heinemann, Oxford, 1994, pp. 315–316). Thespecific gravity values of the three anisotropic stones alsodiffer, and a standard refractometer will give one of therefractive indices (around 1.722) for bastnäsite, whereasgrossular is 1.74 and zircon and sphene are over-the-limitof most refractometers. Examination with a gemologicalmicroscope revealed brown needle-like inclusions inalmost all of the bastnäsite samples; these were recentlyidentified as astrophyllite in bastnäsite from Pakistan (seeG. Niedermayr, “Bastnaesit aus Pakistan—ein neuerSchmuckstein?” Mineralien Welt, Vol. 12, No. 3, 2001, p.51). When exposed to long- or short-wave UV radiation,only the zircon showed fluorescence (yellow), while theother gems were inert. As is typically the case in gemolo-gy, more than one test is necessary to make a positiveidentification.

Dudley BlauwetDudley Blauwet Gems, Louisville, Colorado

Jaroslav Hyrsl

Spinel with clinohumite from Mahenge, Tanzania. TheMahenge region in southern Tanzania is well known forthe marble-hosted ruby deposits found there (see, e.g., J.Kanis, “Morogoro and Mahenge ruby occurrences,Tanzania,” 27th International Gemological Congress


Figure 10. Numerous fibrous inclusions are present inthe cat’s-eye amethyst shown in figure 9, and are ori-ented perpendicular to subtle color zoning. Note alsothe smaller fibrous inclusions oriented at approxi-mately 45° to the main direction. Photo by JaroslavHyrsl; width of view 5.4 mm.

Figure 11. Represented as bastnäsite, this 2.12 ctbrownish yellow-orange stone was identified assphene. Photo by Maha Tannous; courtesy ofDudley Blauwet.

handbook, Mumbai, India, 1999, pp. 70–73). In summer2000, a small mine near the town of Mahenge producedsome attractive spinel specimens—dark purple crystals ina matrix of white marble. The crystals ranged up to about5 cm as octahedrons and, rarely, flattened spinel-lawtwins (figure 12).

Although small portions of the spinel are facetable,the real interest for gemologists lies in an associatedorange mineral, which the dealer presumed was spessar-tine garnet. The specimens show a striking similarity tomaterial from Kuchi-Lal in the Pamir Mountains ofTajikistan—a famous locality for gemmy pink spineland clinohumite. X-ray diffraction analysis confirmedthat the orange mineral from Mahenge was clinohumite,a rare Mg-silicate that is known in cuttable quality fromvery few places in the world. Unlike spessartine (whichhas a hardness of 7–7.5), clinohumite has a hardness ofonly 6 on the Mohs scale. Clinohumite also has differentoptical properties. However, the fastest way to distin-guish the two minerals, both for faceted gems and rough,is with UV fluorescence: Spessartine is inert, whereasclinohumite glows strong orange to short-wave UV radi-ation. The dealer informed this contributor that the bet-ter-quality material had already been cut in Tanzaniaand sold as spessartine.

Jaroslav Hyrsl

An interesting engraved emerald. The 1.72 ct carved andfaceted emerald shown in figure 13 was part of a large par-cel of broken stones that William Larson (PalaInternational, Fallbrook, California) recently purchasedfrom a major jeweler. After several hours of siftingthrough what turned out to be mostly glass and synthet-ics, one of these contributors (RWH) noticed an emeraldthat initially appeared to be badly scratched. Closer exam-ination with a microscope revealed that the table wasactually engraved in Arabic (again, see figure 13). Theengraving translates as “Please God, announce good tid-ings.” Curiously, the writing is engraved in reverse, and

can only be read correctly through the faceted side of thestone. In addition, the facet orientations and inclusions inthe stone make it very difficult to read. However, animpression from the engraved side of the stone (in, forexample, wax) would read in the correct manner, whichleads us to surmise that the stone was once mounted in aring and used as a seal.

The stone measured 9.54 × 7.50 × 2.80 mm, and hadR.I. values of 1.572–1.580. When examined with aChelsea filter, the stone appeared orangy red. Some smallcracks exhibited a weak yellow fluorescence to long-waveUV radiation, but the stone was inert to short-wave UV.Examination with the microscope revealed both a classicthree-phase inclusion and a modified cube of pyrite,which suggests a Colombian origin. A similar engravedColombian emerald was featured on the cover of theSummer 1981 issue of Gems & Gemology: That 217.8 ctMogul emerald was engraved with an Islamic prayer,although not in reverse. Such stones are representative ofthe early Colombian emeralds that were treasured by theMogul nobility in India.

Maha Tannous and John I. KoivulaGIA Gem Trade Laboratory, Carlsbad

[email protected]

Richard W. HughesPala International

Fallbrook, California


Figure 12. Crystals of dark purple spinel from a newfind near Mahenge, Tanzania, were found associat-ed with an orange mineral that proved to be gem-quality clinohumite. The specimen on the right(with the clinohumite) measures 3.5 × 1.5 cm.Photo by Jaroslav Hyrsl.

Figure 13. This 1.72 ct engraved natural emeraldwas found in a large parcel of stones, most of whichwere glass or synthetics. The Arabic inscription wasdone in reverse, so it can only be read through thefaceted stone or as an impression in wax. For thisreason, it is believed that the stone was originallyused in a seal ring. Photo by Maha Tannous.

Unusual rutilated quartz. Rutilated quartz is never inshort supply at the Tucson shows. Faceted stones, cabo-chons, beads, and polished crystals are just some of theforms encountered. While most of this material is com-posed of randomly oriented needles of rutile scattered incolorless or smoky quartz, occasionally an unusual exam-

ple of this relatively common mineral combination isencountered. One of the most sought-after forms of ruti-lated quartz, for jewelry designers in particular, occurswhen the rutile fibers radiate outward from six-sidedblack ilmenite-hematite inclusions. Less well known, andperhaps even rarer than these rutile “stars,” are macro-displays of rutile that form geometric “scaffolds” of elon-gated twinned crystals.

A relatively large rutilated quartz of this latter typewas discovered at the Tucson show booth of Tucson jew-elry designer and lapidary, Kevin Lane Smith. Weighing79.66 ct and measuring 54.4 × 34.9 × 5.2 mm, this unusu-al freeform polished quartz (figure 14) could be used as thecenterpiece in an impressive piece of jewelry. It is alsoattractive under magnification, with the translucent red-brown color of the rutile and the complex branchinggrowth of the twinned sagenitic structure (figure 15)adding an element of intrigue that seems to draw anobserver in for a closer look. While rutilated quartz is rela-tively common, examples such as this are not often seen.

John I. Koivula and Maha [email protected]

Important new ruby deposits in eastern Madagascar:Chemistry and internal features. In January 2001, roughstone buyer Werner Spaltenstein informed staff mem-bers at SSEF that two important new ruby deposits hadbeen found in eastern Madagascar—near Vatomandryand Andilamena. To investigate the new rubies, thiscontributor recently traveled to Chanthaburi, Thailand,where a significant amount of the material is processedand sold (figure 16). Several dozen rough and cut rubies(both heated and unheated) were examined inChanthaburi, and some were selected for further studyat the SSEF laboratory in Basel.

Vatomandry is located east of the capital city ofAntananarivo. The rough from this area is typically asaturated purplish red that responds well to heat treat-ment; it occurs as rounded fragments up to 1 cm (again,see figure 16). Faceted rubies as large as 6 ct have beencut. Microscopic examination revealed veils of fluidinclusions, as well as mineral inclusions formed by iso-lated crystals or clusters of tiny crystals (figure 17, left).Using laser Raman microspectrometry, SSEF identifiedthe minerals in the clusters as zircon; they resemble thezircon clusters commonly seen in gem corundum fromUmba, Tanzania. The larger isolated inclusions wereidentified as apatite (colorless) and rutile (dark orange-brown); the latter also formed oriented needles (silk; fig-ure 17, right). The large individual rutile inclusions areprotogenetic (i.e., formed before the ruby host), whereasthe rutile as silk is epigenetic (i.e., formed after rubycrystallization). Most of the ruby crystals also showedthin twin lamellae in all three rhombohedral directions(see figure 17, left). Trace-element analysis of the tworubies (the lightest and darkest samples available) by


Figure 14. A jewelry designer could use the lightcoppery reflective display of rutile in this 79.66 ctfreeform polished quartz to create an interesting one-of-a-kind brooch. Photo by Maha Tannous.

Figure 15. With magnification (here 5×), the complexbranching growth of the twinned rutile structure isseen in detail. In darkfield illumination, the red-browncolor of the rutile is also apparent. Photomicrograph byJohn I. Koivula.

EDXRF at the SSEF laboratory showed significant Cr(0.6–1.2 wt.% Cr2O3) and Fe (0.5–0.7 wt.% Fe2O3), aswell as smaller amounts of Ti, V, and Ga.

The other new ruby source—near Andilamena—is situ-ated 200 km from the eastern coastline near the town ofAmbatondrazaka. This area is already known for its beauti-ful yellow chrysoberyl twins (see, e.g., F. Pezzotta,Madagaskar, extraLapis No. 17, 1999, pp. 47–48). The rubytypically occurs as euhedral, tabular, saturated purplish redcrystals (again, see figure 16); faceted gems up to 12 ct areknown. Asterism has been seen in some stones. Inclusionsof zircon and rutile (the latter as silk and dark isolated crys-tals) were identified by Raman analysis (figure 18), and scaf-fold-like intersections of twin lamellae were seen with themicroscope. EDXRF analyses of two samples (again, thelightest and darkest) showed significant amounts of Cr(0.4–1.8 wt.%) and Fe (approximately 0.9 wt.%), and smalleramounts of Ti, V, and Ga. HAH

The new ruby deposits in eastern Madagascar: Miningand production. This contributor, who is involved with acompany that is trading material from Vatomandry andAndilamena (see, e.g., figure 19), supplied further detailson accessing and mining these deposits, as well as somepreliminary observations about the rough.

The Vatomandry deposit was discovered in September2000. Access to the mining area, which lies along theSakanila River, requires traveling on a dirt road approxi-mately 30 km southwest of the coastal town ofVatomandry, which is located 140 km south of Tamatave(Toamasina). Most of the rainforest in this area wascleared in the past by periodic slash-and-burn cultivation.

Soon after the ruby discovery, several thousand minersmoved to the region and started mining with basic equip-ment (i.e., shovels and hand-sieves). Many areas, eachmeasuring 1–3 km2, have been worked. So far, the mostproductive area is located near the village of Tetezampaho.The rubies are found in a layer of gravel about 30 cm thickthat generally lies less than 2 m below the surface. Theminers wash the gem-bearing gravel in small rivers usinghand sieves. Grayish or greenish blue sapphires are also

found in the gravel, many weighing 0.5 grams and larger,but initial heat treatment of this material has provedunsatisfactory. The majority of the ruby rough weighs0.1–0.3 grams, and rough stones exceeding one gram arerare. Although most of the rubies are purplish red, someshow an attractive color that is similar to that of fineBurmese rubies. About 30%–40% of the Vatomandryrubies are marketable without heat treatment.

After the initial rush, the Malagasy government closedthe area to mining in February 2001. The closure wasdone to avoid the environmental and tax problems atten-dant to uncontrolled exploitation of the region by thou-sands of independent miners, as has been the case withthe Ilakaka gem rush over the past two years. The mili-tary enforced the closure, and all trading and exporting ofgems from this area were prohibited. Many of the minershave left the region, and ruby production has decreasedsubstantially. The government has since divided the areainto claims (2.5 × 2.5 km each) that will be auctioned tocompanies that meet specific criteria. These criteria wereannounced by the Ministry of Mines in mid-June. Atpress-time, interested companies had until mid-July tobid for claims. The minimum bid for each claim was


Figure 16. These heat-treated rubies are from twonew mining areas in Madagascar: Vatomandry (roughand cut, left) and Andilamena (two crystals on theright; up to 14 mm long). The inset shows parcels ofunheated ruby from Vatomandry (left) and Andila-mena (right). Photos by H. A. Hänni.

Figure 17. The heat-treated rubyfrom Vatomandry on the left con-tains clusters of tiny zircon crys-tals, as well as larger inclusions ofapatite (colorless) and rutile(dark). Also present are partiallyhealed fractures and lines createdby intersecting twin lamellae. Onthe right, partially resorbed silkand zircon clusters are visible inanother heat-treated Vatomandryruby. Photomicrographs by H. A.Hänni; magnified 20×.

around US$30,000, with the claims to be awarded to thehighest bidder. It is difficult to estimate the overall rubyproduction from Vatomandry, because most trading wasdone illegally and the stones were smuggled out of thecountry. This contributor estimates that more than 70 kgof rough have been recovered, and all indications are thatthe region has tremendous potential.

The ruby deposit near Andilamena lies within tropicalrainforest at the eastern margin of the country’s northernhigh plateau (figure 20). The area can be reached only byfoot, following a path that leads about 45 km northeastfrom Andilamena. An exhausting one to two days of trav-el is required to visit the mines. The first rubies were dis-

covered in October 2000, but these were not transparentand appeared over-dark. Better-quality material was foundin January 2001, and a “gold-rush” atmosphere ensued(figure 21). Hundreds of people arrived each day—manyfrom Ilakaka—and began digging unsystematically with-out making any attempt at prospecting. By chance, twoproductive areas were discovered, each about 1–3 km2.Within six weeks, nearly 40,000 miners were working inthe area, digging with very basic equipment, and living inshacks composed of wood and plastic sheeting. Food andprovisions were brought from Andilamena, which alsobecame the headquarters for gem trading. Since foreignbuyers are not allowed into the mining area, many haveset up offices in Andilamena. Most of the buyers are fromThailand, or are related to Thai companies. The Malagasygovernment attempted to close the mining area this pastApril, but their efforts were unsuccessful because of thelarge number of people who are widely scattered through-out the rather inaccessible area. By late June, several ofthe major buyers had left Andilamena and many of theminers had returned to Ilakaka. Nevertheless, there wasstill significant mining and production from the area.

The Andilamena rubies are mined from a layer of grav-el that generally lies 2–3 m below the surface. Ore gradescan be quite high: More than 100 grams of ruby per cubicmeter of gravel have been recovered from some areas. As aresult, large quantities were produced in a short time. Thiscontributor estimates that about 2 tons of all grades ofruby had been mined as of May 2001. Most of this materi-al is fractured throughout and appears over-dark.Nevertheless, a significant amount of transparent red topurplish red material has been found. Most of the roughoccurs as well-formed tabular crystals (which average 0.5gram each) with slightly to moderately rounded edges.Clean, attractive rubies showing fine red color are veryrare, but they can exceed 5 grams. Some sapphire is alsorecovered, as at Vatomandry.

The new ruby deposits of eastern Madagascar probablyshare a similar geologic origin. According to Dr. FedericoPezzotta (Museo Civico di Storia Naturale, Milan, Italy),the area between Vatomandry and Andilamena is knownfor the presence of abundant corundum in metamorphic


Figure 18. This unheated ruby from Andilamenacontains inclusions of dark-appearing rutile crys-tals and colorless zircon crystals. Photomicrographby H. A. Hänni; magnified 20×.

Figure 19. These unheated rubies (the largest is 2.02ct) are from the new deposits in eastern Madagascar.Photo by Elizabeth Schrader.

Figure 20. In the Andilamena area of Madagascar,rubies are mined in a remote location within tropi-

cal rainforest. Photo by Rakotosaona Nirina.

rocks that apparently formed by the interaction of desili-cated granitoid (locally pegmatitic) intrusions with maficand ultramafic host rocks. The ruby crystals do notappear to have undergone significant alluvial transport.Prospecting is hindered by the lack of detailed geologicstudies and the fact that there are few outcrops in eithermining area.

The Malagasy rubies have clearly made a significantimpact on the ruby trade. During a visit to Chanthaburi inlate April 2001, this contributor noted a sharp decrease inthe price of medium- to low-quality rubies, which haveflooded the market there. According to Thai heat treaters,the over-dark colors cannot be lightened by heating.However, heat treatment is successful in removing some ofthe purple component from the lighter-colored material.

Alexander LeuenbergerIsalo Gems & Mining, Antananarivo, Madagascar

[email protected]

Ruby crystal with large mobile gas bubble. SouthernCalifornia gem dealer William Larson is always lookingfor unique or unusual items during his frequent buyingtrips to Myanmar. One such gemological curiosity foundon a recent trip was a 2.46 ct ruby crystal with four ran-domly placed polished flats (figure 22).

This specimen (which measured 7.92 × 5.85 × 5.38mm) was unusual in that it contained a large (almost 4

mm) negative crystal with a 1-mm-diameter free-movinggas bubble (again, see figure 22). Also seen moving withinthe liquid phase were numerous tiny white solid parti-cles, which make this a three-phase inclusion. Althoughboth primary and secondary fluid inclusions are known tooccur in rubies from Myanmar, the very large size of this


Figure 22. This 2.46 ct Burmese ruby crystal con-tains a fluid inclusion with a free-floating 1-mm-diameter gas bubble. Photomicrograph by John I.Koivula; magnified 5×.

Figure 21. In a rush tostake their claims, tensof thousands of minershave journeyed to theAndilamena area. Therubies are mined bysimple methods from alayer of gravel that typi-cally lies 2–3 m belowthe surface. Photo byRakotosaona Nirina.

primary negative crystal, and the mobility and size of thegas phase and the mobile solid phase(s) inside it, are espe-cially noteworthy.

It is fortunate that the inclusion was not damagedduring placement of the polished faces. Large fluidinclusions are very sensitive to heat, and significantheat can be generated by friction during cutting. Also,since the precise extent of this fluid inclusion in theruby is not clearly visible, the chamber could easilyhave been opened during the grinding of the flats, caus-ing the fluid to drain out.

John I. Koivula andJo Ellen Cole

GIA, Carlsbad

A brownish green sapphire, with pyrochlore inclusions. Alarge, slightly brownish green sapphire, reportedly fromMyanmar, was recently seen in both the AGTA laborato-ry in New York and the GIA Gem Trade Laboratory inCarlsbad. The gem, an oval mixed cut that weighed 28.04ct and measured 18.80 × 17.28 × 10.89 mm (figure 23),was brought to our attention by Joseph Krashes, ofKrashes Dirnfeld, New York. It was interesting not onlybecause of its size and color in relation to the stated local-ity, but also because of the inclusions it contained.

The sapphire played host to a number of transparentto translucent brownish yellow inclusions (figure 24), afew of which had been exposed to the surface duringfaceting. When we examined some of the inclusions withhigher magnification using a digital camera attached to aRaman microscope, we observed a crystal form that sug-gested that they were isometric, and no pleochroism wasvisible with polarized light. The slightly rounded surfaceof the inclusions suggested that dissolution might haveoccurred prior to their incorporation into the sapphire.The transparency and general condition of these inclu-sions and their immediate surroundings indicated thatthe host sapphire had not been subjected to high-tempera-ture heat treatment—an important consideration intoday’s sapphire market.

Laser Raman microspectrometry of the inclusions atboth laboratories identified them as pyrochlore. In thepast, the pyrochlore inclusions we have encountered insapphires have always been dark red to brownish red andobserved in blue to blue-green sapphires (see, e.g., figure25). This is the first time that either laboratory has identi-fied brownish yellow pyrochlore inclusions in sapphire ofany color. John I. Koivula and K. Scarratt

Update on the Vortex sapphire mine, Yogo Gulch,Montana. Last summer, this contributor revisited theVortex sapphire mine at Yogo Gulch, Montana, for thefirst time since 1995 (see K. A. Mychaluk, “The Yogo sap-phire deposit,” Spring 1995 Gems & Gemology, pp.28–41). Vortex Mining Co. provided unrestricted access totheir operation. Since 1995, there has been a considerableexpansion in surface equipment, manpower, and safetymeasures, as described in this update.

A new steel head frame (figure 26; compare with figure12 in Mychaluk, 1995) has been erected, which greatlyimproves haulage capacity from the underground work-ings. Ventilation ducts and fans now provide air circula-tion to the entire mine. In addition to the 76-m-deep mainshaft (erroneously reported as 61 m deep in Mychaluk,1995; depth unchanged since then), a new tunnel is beingexcavated from the lowest levels to the surface, givingminers increased ventilation and an alternate escape route.Compressed air and electricity are now available on eachlevel, and several mine phones have been added. As in thepast, very few timber supports were observed in the mine,because of the competency of the limestone host rock. At


Figure 24. Raman analysis identified these brown-ish yellow inclusions in the brownish green sap-phire shown in figure 23 as pyrochlore. Photomicro-graph by John I. Koivula; magnified 15×.

Figure 23. This 28.04 ct natural sapphire was inter-esting because of its size and color in relation to thestated locality, Myanmar, and because of the inclu-sions it contained. Photo by Kenneth Scarratt.

press time a crew of nine was working, and as many as 14miners worked the mine last winter.

The underground workings follow two distinct, sub-parallel sapphire-bearing dikes (described as E and F byMychaluk, 1995), which are more than 70 m apart. Toexcavate the sapphire-bearing ore, the miners drive hori-zontal tunnels into each dike and then stope upwards. Atunnel at the 76 m level has now advanced 80 m alongthe E dike, with large stopes reaching almost to the sur-face. A new crosscut (i.e., a tunnel driven at a right angle tothe dikes), also at the 76 m level, has reached the previous-ly unmined F dike, and another horizontal tunnel hasexplored about 30 m of this dike. Again, large stopes extendupward from this level. A natural cave system, which isactively forming in the limestone adjacent to the dikes,has been exposed at the 76 m level; the layered floor sedi-ments in the cave contain fragments of sapphire-bearingdike rock. The mine yielded 60,000 carats of gem-qualitysapphire rough during the period 1995–2000. To helpincrease production, Vortex has begun excavating a 900-m-long access tunnel (a “decline”), which is currently 460m long and has reached a level of 82 m below the surface.

The thickness of both the E and F dikes varies widely,although they are predominantly 0.25–0.5 m wide.Xenoliths of limestone host rock are locally present with-in the dikes. The miners have worked around theseobstructions, leaving them as pillars within the tunnels.Very little contact metamorphism was noted between thelimestone country rocks and the dike rocks. All of thesapphire-bearing dike rock observed in situ was deeplyweathered (to clay and carbonate minerals). Because thismaterial is soft and friable, it is easily mined. Limited

blasting breaks up the ore, which is then loaded into orecarts, transported to the elevator, and brought to the sur-face. The procedure for processing the ore was unchangedfrom that described in Mychaluk (1995), although a newmill with 200-ton-per-day capacity began operating inmid-June 2001. Sapphire grains as small as 2 mm werebeing collected in Vortex’s gravity-separation plant,which suggests efficient recovery.

A large selection of rough and faceted sapphires andfinished jewelry was seen at the mine site. Except for afew well-saturated purple sapphires, all of the stones(none of which had been heat treated) were a consistent“cornflower” blue. Most notable were a 2.78 ct oval-cutsapphire and a 3 ct rough stone, both from the F dike,which are large for Yogo sapphires. Most of the rough issent to Bangkok for faceting; only larger stones are cutlocally. Vortex continues to manufacture their own lineof jewelry using contract goldsmiths.

Keith A. Mychaluk

Canary tourmaline from Malawi. A new deposit of“electric” yellow and greenish yellow tourmaline wasdiscovered in fall 2000 in Malawi. The bright yellow


Figure 25. In contrast to their brownish yellowcolor in the sapphire shown in figure 24, pyrochloreinclusions in blue sapphire typically are darkbrownish red. Photomicrograph by John I. Koivula;magnified 20×.

Figure 26. Many improvements have been made atthe Vortex sapphire mine at Yogo Gulch, Montana,over the last several years, including this new steelhead frame. Photo by K. A. Mychaluk.

gems are being marketed as “Canary” tourmaline (figure27). Although some of the material is natural color,much of it has been heat treated to achieve the “elec-tric” yellow color. Before treatment, this rough wasbrown to brownish yellow. Because the tourmaline typi-cally contains black needle-like inclusions, 95% of therough yields faceted gems that are less than one carat.Most of the finished stones are 0.10–0.50 ct, in a varietyof calibrated shapes. Production has been quite steady atapproximately 1,000 carats per month. Currently, 95%of the production is being sold in Japan, but more maybe available by the 2002 Tucson show.

The gemological properties of this material (obtainedon two samples by Shane McClure, director ofIdentification Services at the GIA Gem Trade Laboratoryin Carlsbad) were consistent with those for most gemtourmalines: R.I.—1.620–1.641, S.G.—3.10, inert to long-and short-wave UV radiation, weak dichroism (light yel-low and moderate yellow), and no distinct featuresobservable with a desk-model spectroscope. Microscopicexamination revealed only a few small liquid “finger-prints” and some transparent crystal inclusions. (Theblack needles usually are removed during cutting.)

Microprobe analysis of the 2.08 ct sample by Dr. W.“Skip” Simmons at the University of New Orleansrecorded an enrichment in manganese (6.93 wt.% MnO),fluorine (2.02 wt.% F), and titanium (0.45 wt.% Ti) in thiselbaite (all values represent an average of four analyses).Also significant were calcium (0.63 wt.% CaO) and iron(0.13 wt.% FeO). Other elements were either present invery minor amounts or were not detected: K, Mg, V, Cr,Zn, Ba, Pb, and Bi. The composition of this bright yellowtourmaline suggests that its color is due to Mn2+–Ti4+

intervalence charge transfer (see G. R. Rossman and S. M.Mattson, “Yellow, Mn-rich elbaite with Mn-Ti interva-lence charge transfer,” American Mineralogist, Vol. 71,1986, pp. 599–602). The enriched manganese content isnoteworthy, but the sample analyzed does not containenough of this element to attain the theoretical Mn-tour-maline end member called “tsilaisite” (i.e., 10.7 wt.%MnO; see J. E. Shigley et al., “A notable Mn-rich gemelbaite tourmaline and its relationship to “tsilaisite,”American Mineralogist, Vol. 71, 1986, pp. 1214–1216).

Edward Boehm Joeb Enterprises, Solana Beach, California

[email protected]

A bismuth-bearing liddicoatite from Nigeria. In a parcel ofgem tourmaline from Nigeria (Ogbomosho area) pur-chased by faceter Nancy Attaway (Sandia Park, NewMexico) in January 1999, this contributor noticed somecrystals with unusual coloration: a pale orangy pink coresurrounded by a purplish pink rim (figure 28). To investi-gate the cause of the orangy pink color, one of the small-er, slightly abraded (eluvial) crystals was selected for elec-


Figure 28. This 5.87 ct crystal of tourmaline fromNigeria has a most interesting chemical composi-tion. It was selected from a parcel of gem tourma-line that was purchased in January 1999 by NancyAttaway, who subsequently donated it to GIA.Photo by Paul Hlava; inset photo by Maha Tannous.

Figure 27. Bright yellow “Canary” tourmaline isbeing mined from a new deposit in Malawi. Most of

the finished gemstones weigh less than 1 ct, andhave been heat treated to remove the brown color

component. These stones weigh 2.08 and 2.82 ct(bottom; courtesy of Joeb Enterprises) and 11.65 ct

(top; courtesy of Pala International); photo by MahaTannous.

tron microprobe analysis. One surface perpendicular tothe c-axis of this 5.87 ct crystal was ground and polished,so that the entire 6-mm-diameter cross-section could beanalyzed. Gemological properties, collected by GNI editorBrendan Laurs, are as follows: R.I.—1.620–1.638, birefrin-gence—0.018, S.G.—3.07, and UV fluorescence—inert tolong-wave radiation and moderate yellow to short-wave(on the outer “skin” of the prism faces only). Microscopicexamination revealed feathers, planes of fluid inclusionson partially healed fractures, and a few colorless, low-relief, birefringent mineral inclusions.

The microprobe analyses were obtained at the SandiaNational Laboratories in Albuquerque, New Mexico,using a JEOL 8600 instrument controlled by theSandiaTask operating system; data processing was accom-plished using the Bence-Albee correction procedure.Initial observations of a few analyses revealed:

1. The pink rim contains Mn, whereas the orangy pinkcore contains both Mn and Fe.

2. The tourmaline generally contains little Na, Mg, andFe, and is enriched in Ca, which suggests that it is lid-dicoatite.

3. Elevated Bi contents are present throughout the crys-tal, particularly in the rim.

To chemically characterize the material and especiallythe two color zones, 557 points were analyzed across thewidth of the polished face. Several major and trace ele-ments were measured: Na, Mg, Al, Si, Ca, Mn, Fe, Zn,and Bi; Cr and Zn were also analyzed, but were below thedetection limits of the instrument (i.e., less than approxi-mately 0.03 wt.% Cr2O3 and 0.13 wt.% ZnO). Mineralstandards and synthetic element oxides were used to stan-dardize the instrument and obtain quantitative analyses.

The analyses reveal that the outer rim of the crystalconsists of Ca-rich elbaite, whereas the inner part of therim and the core is liddicoatite with up to 4.60 wt.% CaO(figure 29); this is more calcium-rich than the type speci-men of liddicoatite from Madagascar (4.21 wt.% CaO; seeP. J. Dunn et al., “Liddicoatite, a new calcium end-mem-ber of the tourmaline group,” American Mineralogist,Vol. 62, No. 11/12, 1977, pp. 1121–1124). Also surprisingis the amount of bismuth enrichment: Besides the rela-tively high Bi contents in the core (averaging about 0.3wt.% Bi2O3), up to 1.23 wt.% Bi2O3 was measured in therim. This is apparently the first mention of Bi in liddicoat-ite, and the enriched rim contains much more Bi than hasbeen reported for elbaite in the gemological literature todate (compare up to 0.83 wt.% Bi2O3 in E. Fritsch et al.,“Gem-quality cuprian-elbaite tourmalines from São Joséda Batalha, Paraíba, Brazil,” Fall 1990 Gems & Gemology,pp. 189–205). In general, Bi levels in the crystal areinversely proportional to Ca contents. Iron was notdetectable (<0.05 wt.% FeO) in the rim of the crystal, andonly small amounts of Fe (up to 0.12 wt.% FeO) are pre-sent in the core. Manganese is also relatively depleted in

this tourmaline, with the highest values measured in thecore (0.45 wt.% MnO). The orange modifier in the core ofthis pink tourmaline appears to be caused by both Mn andFe; the highest concentrations of these elements are pre-sent in the core, and none of the other elements detectedis a known chromophore in tourmaline.

Elbaite and liddicoatite cannot be differentiated bycolor or standard gemological testing. The interestingchemical data collected from this single sample make onewonder how much of the tourmaline from Nigeria (andelsewhere) is actually liddicoatite.

Paul F. Hlava Sandia National Laboratories

Albuquerque, New [email protected]

SYNTHETICS AND SIMULANTS“Jurassic Bugs” amber imitation. Gemological curiositiesabound at the Tucson gem and mineral shows in Februaryeach year. Many of these are discovered “off the beatenpath” and take the form of treated stones, synthetics, orimitations. Such items may be of interest to a laboratory


Figure 29. Electron microprobe data (557 analyses)across the Nigerian tourmaline crystal revealedthat the outer part of the purplish pink rim is Ca-rich elbaite, and the pale orangy pink core is liddi-coatite. Elevated contents of Bi are present acrossthe entire crystal, but particularly high values (upto 1.23 wt.% Bi2O3) were measured in the rim.

gemologist as reference specimens, particularly if theyhave not been encountered previously.

This past February we had the opportunity to pur-chase three samples of cast-plastic amber substitutes,each of which contained one insect, which were beingsold as “Jurassic Bugs.” As seen in figure 30, these pol-ished nodules are a very convincing transparent, slightlybrownish yellow, somewhat reminiscent of much of thetransparent natural amber from the Dominican Republic.However, the condition and almost perfect positioning ofthe insect inclusions in the nodules would have raisedour suspicions, even if the material had not been market-ed as imitation amber at a very low price.

The dealer had a basket of these nodules, which werepackaged individually in small plastic bags. Each had apaper “Jurassic Bug” label imprinted with a cartoon-likemosquito. The choices were ant, ladybug, or mosquito(again, see figure 30). The nodules are formed as plasticblocks. When the plastic is still soft, a depression is creat-ed in the surface, the insect is placed and positioned, and asecond layer of plastic is added to cover the depression.Then the blocks are rounded off into freeform nodules andpolished. The end result is an interesting amber substitute.

Gemologically, the nodules test as plastic. The spotR.I. was consistent at 1.56, which is slightly higher thanthe 1.54 expected for amber. Unlike amber, all three nod-ules sank readily in a saturated salt solution, and there wasno visible-light absorption spectrum. The nodules fluo-resced a weak, slightly chalky bluish green to long-waveUV radiation, with no reaction to short-wave UV. In addi-tion, the zone of encapsulation created by the depressionand secondary pour of plastic was easily seen when theinsects were examined in polarized light (figure 31).

“Jurassic Bugs” are an interesting amber substitutethat is easily separated from natural amber using standardgemological tests and observational skills.

John I. Koivula and Maha Tannous

Deceptive assembled diamond imitations from Brazil. LastJanuary, a client submitted two pieces of rough (8.71 and23.57 ct; figure 32) to SSEF for identification. They wererepresented to him as diamonds in Brazil, where he pur-chased them for US$500. A dealer there used a diamond


Figure 32. Represented as diamond rough in Brazil,these imitations consist of topaz (23.57 ct, left) andcubic zirconia (8.71 ct, right) to which small frag-ments of diamond have been attached in discretecrevices. The seller could then place a diamond probeon the small piece of diamond to “prove” that theentire piece was “natural.” Photo by H. A. Hänni.

Figure 30. These three freeform brownish yellowplastic nodules were sold as novelty substitutes fornatural amber. A single insect is encapsulated ineach. The largest nodule, at the bottom of thisphoto, weighs 8.43 ct and contains a mosquito. Theother two insects seen here are a ladybug and anant. Photo by Maha Tannous.

Figure 31. Magnification and polarized light reveal thezone of encapsulation and the strain pattern thatdeveloped when this 7-mm-long ant was encased inliquid plastic that subsequently solidified. Photo-micrograph by John I. Koivula.

probe to “confirm” that the stones were diamonds. Bothlooked like broken crystal fragments, and they did not ini-tially appear to be imitations.

The 23.57 ct stone was approximately 14 × 14 × 11mm, and had an S.G. of 3.56 (measured hydrostatically);this was identified as topaz. The 8.71 ct sample wasapproximately 10 × 8 × 7 mm, with an S.G. of 5.89; it wasidentified as cubic zirconia. (Both identifications were con-firmed with laser Raman microspectrometry.) Whenexposed to long-wave UV radiation, the 8.71 ct sampleshowed one spot that fluoresced blue. Microscopic exami-nation revealed that the fluorescent area corresponded to a2 × 1.5 mm colorless fragment that was attached to thesurface (see inset, figure 32); testing with a diamond probeindicated that this fragment was diamond, which was con-firmed by Raman analysis. Further examination of the23.57 ct sample revealed that it also had a diamond frag-ment attached to its surface; in this case, the 2 × 2 mmfragment did not show any fluorescence. On both samples,the pieces of diamond were glued into notches where thedealer could easily place the diamond probe, making themparticularly deceptive imitations. HAH

Enamel-backed quartz as a star sapphire imitation.Recently these contributors received an approximately 10ct blue cabochon for testing. The stone displayed nice,distinct asterism and was mounted in a ring with dia-monds. On first sight, it resembled a star sapphire (figure33). Closer examination with a microscope, however,revealed features that indicated it was an imitation.

The back of the stone was flat and appeared bruted.Star stones typically have a bruted back that is domed,not flat. With the microscope, it became obvious that theblue color was located solely in a thin (about 1 mm) layeron the base of the cabochon. This layer had a grainyappearance with many air bubbles (figure 34, left). It couldnot be scratched with a needle. The upper part of thecabochon consisted of a colorless transparent materialthat contained three sets of tiny colorless needlesarranged at 120° angles (figure 34, right). These were thecause of the distinct asterism.

No inclusions typical of sapphire (e.g., negative

corundum crystals, mica, or zircon with tension frac-tures) were observed in the sample, although small con-choidal fractures (which are unusual for sapphire) wereobserved. We also did not see the expected absorptionline for sapphire at 450 nm with a desk-model spectro-scope; in fact, no distinct absorption bands could beseen. When we examined the cabochon with a polar-iscope, however, we easily recognized a so-called bull’s-eye figure, which is typical for quartz. EDXRF qualita-tive chemical analysis and Raman analysis confirmedthe identification as quartz.

Although the imitation had a convincing appearance,standard gemological and laboratory testing revealed thatit was a star quartz backed with a layer of blue enamel.This is the first time that we have seen such an elaborate,high-quality imitation of a star sapphire.

Michael S. Krzemnicki and HAH SSEF Swiss Gemmological Institute

[email protected]


Figure 33. This imitation star sapphire was mounted ina ring with diamonds. Photo by H. A. Hänni.

Figure 34. The blue enam-el layer at the base of thequartz cabochon, whichprovided the color, con-tained numerous gas bub-bles (left). Tiny needle-like inclusions wereresponsible for the aster-ism in the quartz (right).Photomicrographs by H.A. Hänni; magnified 30×.

MISCELLANEOUS11th Annual V. M. Goldschmidt Conference. This year’sGoldschmidt geochemistry conference was held in HotSprings, Virginia, May 20–24, and included a session titled“Geochemistry and Mineralogy of Gemstones.” The ses-sion was well attended, which indicated increasing inter-est in the study of gem materials on the part of the geo-science community. Dr. G. Harlow (American Museum ofNatural History, New York City) introduced the sessionwith a talk on the opportunities that the study of gemmaterials provides for research and for cross-fertilization ofideas between education and the popular culture. As anexample, he cited the American Museum’s recent “Natureof Diamonds” exhibition, which introduced many in thepublic to the science of diamond origin and the technologi-cal applications of diamonds, as it dazzled them with dia-mond jewelry. Next, Dr. J. Shigley discussed the identifi-cation challenges posed by HPHT-annealed diamonds.Recognition of this kind of treatment is increasinglydependent on the use of visible, infrared, and Raman (pho-toluminescence) spectroscopic techniques. Dr. T. Häger(Johannes-Gutenberg-Universität, Mainz, Germany)described experiments to study the causes of color andheat-treatment behaviors of rubies and sapphires. He pre-sented a graphical representation of sapphire colorationaccording to various chromogens (Mg2+, Ti4+, and Fe2+/3+).M. Garland (University of Toronto, Ontario, Canada)reported on the use of trace-element data and inclusion

chemistry to help determine the original source ofMontana’s alluvial sapphires. She suggested that theyformed as a result of contact metamorphism, possiblyrelated to extensive plutonism in this region during theCretaceous Period. Dr. L. Groat (University of BritishColumbia, Vancouver, Canada) described the geologic set-ting of a new emerald occurrence, called the CrownShowing, in the southeastern portion of the YukonTerritory in Canada. The emeralds are hosted by quartzveins in schists. Dr. S. Sorensen (National Museum ofNatural History, Smithsonian Institution, Washington,DC) reported on research into the chemical composition ofjadeite-bearing rocks from Nansibon, Myanmar. Studyingthe rare-earth elements in these jadeitites helps provide arecord of their deformation and recrystallization. C.Wright (Miami University, Oxford, Ohio) discussed thecause of color and paragenesis of several generations of flu-orite from the Hansonburg mining district in NewMexico. Dr. E. Fritsch (University of Nantes, France)described work on volcanic Mexican opals, which differ intheir microstructure from sedimentary gem opals.Sedimentary play-of-color opals are composed of stackedsilica spheres in a regular arrangement, whereas volcanicopals display a wider variety of less-regular micro- andnano-structures. Dr. G. Rossman (California Institute ofTechnology, Pasadena) ascribed the coloration of rosequartz to the presence of microscopic fibrous inclusions ofan unidentified pink mineral thought to be related todumortierite. Translucent blue quartz also appears to becolored by microscopic inclusions—of rutile, ilmenite, orsimilar iron-titanium oxides. Dr. P. Heaney (PennsylvaniaState University, University Park) proposed that tiger’s-eyequartz forms by the fracturing of a crocidolite host rockand deposition of columnar quartz (and enveloped crocido-lite inclusions) in the resulting cracks. Incorporation ofabundant parallel crocidolite inclusion trails into thequartz results in the tiger’s-eye appearance of the rock.

A highlight of the conference was the award of theDana Medal to Dr. George Rossman (professor of miner-alogy at the California Institute of Technology and amember of the G&G Editorial Review Board and GIABoard of Governors) by the Mineralogical Society ofAmerica (figure 35). This award is given to recognize con-tinued outstanding scientific contributions to the miner-alogical sciences; in this case, it was awarded in recogni-tion of Dr. Rossman’s many contributions to this field,particularly regarding mineral spectroscopy and the caus-es of color in minerals. JES

Gemological conference at the Moscow StateGeoprospecting Academy. On April 2–6, 2001, a gemo-logical meeting was held in Moscow as part of an interna-tional conference with the general theme “New Ideas inthe Earth Sciences.” The conference was sponsored byseveral organizations, including the Ministry of Educationof the Russian Federation, the Russian Academy of


Figure 35. At the 11th Annual V. M. GoldschmidtConference, Dr. George Rossman received the presti-gious Dana metal. He is shown here on the right withDr. Cornelius Klein, president of the MineralogicalSociety of America. Photo by Dr. J. Alex Speer.

Sciences, and other professional societies. The gemologi-cal session was organized by the Moscow StateGeoprospecting Academy, the Russian GemologicalInstitute, and GIA Moscow. More than 300 participantsattended the conference, including scientists, governmentofficials, educators, academics, and students from manyregions of the Russian Federation and adjoining countries,as well as some foreign guests.

The presentations covered a wide range of topics,such as the identification of synthetic and treated gemmaterials, chemical and physical properties of gem-stones, new gem materials, and methods for gemappraisal and prospecting. A few of the presentations aresummarized here. The meeting organizers publishedabstracts of all presentations (nearly all in Russian) in aconference proceedings.

Dr. J. Shigley (GIA Research, Carlsbad, California)opened the gemological session with a review of the iden-tification of synthetic and treated diamonds, includingthose that had undergone HPHT annealing. Dr. V. Vins(Institute of Mineralogy and Petrography, Novosibirsk)and others reported on possible color changes that can beproduced by the HPHT-annealing of various types of dia-monds. Y. Shelementiev and co-authors (LomonosovMoscow State University) discussed spectroscopic andluminescent properties as identification criteria for gem-quality synthetic diamonds and HPHT-treated diamonds.Dr. M. Meilman and Dr. E. Melnikov (Moscow StateGeoprospecting Academy and GIA Moscow, respectively)discussed the identification of synthetic moissanite.Several presentations covered the properties of diamondsfrom various areas of Russia as well as studies of theirinclusions. Mineralogical and gemological descriptions ofgem materials from Russia and Central Asia were provid-ed for alexandrite, apatite, charoite, chrysoberyl, sapphire,scapolite, sunstone (feldspar), tourmaline, turquoise, andzircon.

Dr. V. Bukanov (Gemological Association of Russia,St. Petersburg) described his work on a gemological dictio-nary. Dr. V. Balitsky (Institute of Experimental Mineral-ogy, Moscow) reviewed the status of synthetic gem mate-rials produced in Russia and adjoining countries. Dr. L.Demianets (Institute of Crystallography, RussianAcademy of Sciences, Moscow) described her work onsynthesizing various colors of synthetic beryl, includingred. Several gem identification techniques were discussedduring the conference, including the presentation by Dr.S. Mikhailov and others (Institute of Electrophysics, UralDivision, Russian Academy of Sciences, Ekaterinburg)that described a pulsed-laser instrument for recording thecathodoluminescence spectra of gems.

A number of presentations focused on the use of gemsin jewelry and for ornamental purposes. Among thesewere descriptions of museum gem collections, such as theHermitage in St. Petersburg. Various investigators (includ-ing Dr. Julia Solodova and others at GIA Moscow) report-

ed on methods of quality grading colored gemstones suchas ruby, sapphire, and emerald. Methods to appraise pearlsand other nontransparent gem materials also were dis-cussed. B. Borisov and L. Tsunskaya (Moscow HallmarkOffice) reviewed efforts to implement an internationallyrecognized diamond grading system within the RussianFederation. The final presentations covered aspects ofprospecting for various gem materials. The success of thegemological session promises that similar meetings willbe held at future geological conferences in Moscow.

Julia SolodovaGIA Moscow, Russia

([email protected])

JES

A visit to the Harvard tourmaline exhibit. A new exhibit,“Romancing the Stone: The Many Facets of Tourmaline,”opened on February 10, 2001, at the Harvard Museum ofNatural History. Curated by Dr. Carl Francis, this exhibitis the perfect vehicle for displaying Harvard’s extensivecollection of tourmalines, which dates from 1892 whenthe museum accepted the historically importantAugustus Hamlin collection of Maine tourmalines. Infact, the viewer is drawn into the exhibit with the mininghistory of southwestern Maine’s Mt. Mica and Duntondeposits. This section includes impressive crystal speci-mens, beautiful cut stones, and the famous HamlinNecklace, which incorporates 70 tourmalines of differentcolors weighing a total of 228.12 carats.

The exhibit also explores the geology of tourmalineformation and occurrence, with examples of rough andcut tourmaline specimens from most sources worldwiderepresented. In addition, the complex chemical composi-tion of the different tourmaline species is demonstrated ina clever interactive display. An impressive light boxshows several multicolored liddicoatite slices to greatadvantage, and there are many beautiful examples of tour-maline carvings through the ages, notably from China andGermany. Compact, yet thorough, this interesting exhibitwill remain on display through January 20, 2002.

Elise B. Misiorowski Director, GIA Museum

[email protected]

ANNOUNCEMENTS AGTA announces changes to Spectrum Awards. TheAmerican Gem Trade Association has announced signifi-cant changes to its Spectrum Awards, the annual competi-tion for natural colored gemstone and cultured pearl jewel-ry design. Formerly limited to design entries, the 2002Spectrum Awards will include AGTA’s Cutting Edge lap-idary arts competition. Another major difference is thatdesign entries will be judged in fashion categories (evening,business, casual, men’s, and bridal) rather than by price.


Additionally, there will be no limit on the number ofentries allowed, and the judging panel has been expandedfrom three judges to five. The deadline for entering the2002 Spectrum Awards is September 28. To obtain anentry form, visit www.agta.org or call 800-972-1162.Outside the U.S., call 214-742-4367.

New Brazilian gemological maps available. The nationalgeologic survey of Brazil (CPRM—Serviço Geológico doBrasil) recently issued two new gemological maps as partof the series Informe de Recursos Minerais—Série PedrasPreciosas, which started in 1997. Published in 2000, themaps cover the states of Rio Grande do Sul (No. 5) andSanta Catarina (No. 6) at 1:1,000,000 scale, and areaccompanied by detailed reports (in Portuguese) describ-ing the gem resources. Other maps in the series includeportions of Rio Grande do Sul (Nos. 1 and 3), theLajeado/Soledade/Salto do Jacuí region (No. 2), andPiauí/Maranhão (No. 4). To order, visit the CPRM’s onlinebookstore at http://www.cprm.gov.br/didote/cdot01.htm,e-mail [email protected], or fax 55-21-295-5897.

Large natural pearl. Last April, an 845 ct natural pearlmeasuring 62 × 53 × 30 mm (figure 36) was discoveredat the Mukkalauk exploration area near ZadetkyiIsland, which is off the southern tip of Myanmar (seewww.myanmar.com/pearl/pearl.html). According tothis source, the nacreous pearl is the world’s largestnatural pearl. Myanmar Andaman Pearl Co. Ltd., acompany working under a profit-sharing agreementwith Myanma Pearl Enterprises, discovered the pearl,which was found in a Pinctada maxima oyster. It isconsiderably larger than the “Pearl of Asia” (605 ct),which has been reported in the literature as the world’slargest pearl. GIA has not examined the new specimen.

PCF rock-breaking technology. Rockbreaking Solutions hasdeveloped a new technology that offers the mining industrya non-explosive method for the controlled breakage of hardrock. The process, called PCF (Penetrating Cone Fracture),uses a propellant cartridge placed in a drill hole to producea high-pressure gas pulse. The gas expands within smallmicrofractures created during the percussive drilling pro-cess, and fractures the rock in a cone-shaped pattern (seewww.rockbreakingsolutions.com). This non-explosive,low-hazard excavation technique has obvious applicationsfor mining gems from many types of primary deposits.

CONFERENCESWorld Diamond Conference. The 2nd Annual WorldDiamond Conference will attract explorers, producers,investors, and brokers to Vancouver August 22– 23.Presentations will cover the global diamond marketand exploration initiatives, government relations, dia-mond valuation, “conflict” diamonds, and activities inseveral important diamond-producing countries. Visithttp://www.iiconf.com.

Facets 2001. The 11th annual gem and jewelry show orga-nized by the Sri Lanka Gem Traders Association will takeplace September 3–5 in Colombo. Tours to Ratnapura,Elahera, and other mining areas are being organized, aswell as visits to local lapidaries and jewelry manufacturingcenters. Visit http://www.facets-x.com.

Hong Kong Jewellery and Watch Fair. On September 21–25,this show will take place in the Hong Kong Convention andExhibition Centre. Special events include workshops andseminars by GIA, the Gemmological Association of HongKong, and the Diamond High Council, and an exhibition ofTahitian Pearl Trophy Design Competition by Perles DeTahiti. E-mail [email protected] or visitwww.jewellery-net-asia.com.

On Sunday, September 23, Gems & Gemology EditorAlice Keller will participate in GIA GemFest with notedG&G authors Jim Shigley and Tom Moses.

ISA Antique and Period Jewelry course. The Inter-national Society of Appraisers (ISA) will conduct anAntique and Period Jewelry course on September29–October 4 in Atlanta, Georgia. Appraisers, dealers, andcollectors will learn to identify period pieces from beforethe 17th century to the mid-20th century. The coursefocuses on the history, design elements, construction,gem materials, and makers prominent in each period. Call888-472-4732, e-mail [email protected], or visitwww.isa-appraisers.org.

Fourth international business conference in Russia.Russian Precious Metals and Gemstones Market: Today’sSituation and Future Developments will take placeNovember 1–3 in Moscow.


Figure 36. This 845-ct (62 × 53 × 30 mm) naturalpearl was recently discovered near Zadetkyi Islandof southern Myanmar. Photo courtesy of MyanmaPearl Enterprise.

This conference will cover a wide range of topics per-taining to gemstones and precious metals, includingexploration and resource calculation, mining invest-ment, production, certification, legislation, taxation, andcurrent and future markets. Participants will have anopportunity to visit the Kremlin, Diamond Fund ofRussia, St. Basil’s Cathedral, and museums. Visithttp://www.jewellernet.ru/goldenbook/eng/rdmk.html.

EXHIBITSDiamonds exhibition in Canada. Quebec’s Musée de laCivilisation is hosting a special exhibition on diamondsuntil January 6, 2002. This comprehensive exhibitionexamines the properties, geologic formation, and miningof diamonds, as well as their use in jewelry and industrialapplications. Half of the objects on display have beenloaned from New York’s American Museum of NaturalHistory, which developed the Nature of Diamonds exhi-bition. On display are pieces of extraordinary jewelry anddiamonds, including the Aurora Collection, which con-sists of over 260 colored diamonds. Call 418-692-1151, e-mail [email protected], or visit www.mcq.org.

Carnegie Gem & Mineral Show. The Carnegie Museum ofNatural History in Pittsburgh, Pennsylvania, will hold itsfourth annual gem and mineral show August 24–26. Goldis the theme of this year’s show, and some fine specimenswill be displayed by six invited museum exhibitors. Visitwww.clpgh.org/cmnh/gemshow.

Pearls at the American Museum of Natural History. Acomprehensive exhibition on pearls will take place at theAmerican Museum of Natural History in New York fromOctober 13, 2001 to April 14, 2002. The exhibition willshowcase a variety of pearls and pearl-forming mollusks,including white and black pearls from marine Pinctadaoysters of Japan and Polynesia, freshwater pearls frommussels found in the United States and China, pinkconch “pearls” from the Caribbean Queen conch, andmore. A section on the decorative use of pearls will fea-ture an extensive collection of jewelry and objets d’art.Visit www.amnh.org, or call (212) 769-5100.

ERRATA

1. In the Spring 2001 article on the Argyle diamond mine byShigley et al., figure 3 (p. 28) shows two kimberlites locatednear the Argyle mine. These should have been indicated aslamproites. We thank Dr. Bram Janse for this correction.

2. In the Spring 2001 article on hydrothermal synthetic redberyl by Shigley et al., the Y-axis of each graph in figure 14 (p.52) should be labeled “Log (Counts)”. Our thanks to Dr.George Rossman for bringing this to our attention.

3. In the Spring 2001 (p. 86) abstract of the article by B. Zhanget al. (“A study of photoluminescence spectrum of blackpearl,” China Gems, Vol. 9, No. 4, 2000, pp. 111–113), an edit-ing mistake changed the meaning of the second paragraph. Itshould have been stated that the dyed-black freshwater cul-tured pearls exhibited the same photoluminescence featuresas those of untreated freshwater cultured pearls.


GEMS & GEMOLOGY'S TWENTY YEAR INDEX, your indispensable reference guide to the 1981–2000 issues, is now available. Search the index by subject or author to locate the articles, Lab Notes, and Gem News entries of interest to you.

Printed copies are on sale for only $9.95 in the U.S. ($14.00 elsewhere). Download the index FREE OF CHARGE from the G&G website, www.gia.edu/gandg.Or receive a free index by purchasing any three years of back issues.

To order your printed copy of the TWENTY YEAR INDEX, contact Subscriptions Manager Debbie Ortiz at [email protected], or call toll-free 800-421-7250 ext. 7142. Outside the U.S. and Canada, call 760-603-4000, ext. 7142. Back issues and article reprints are also available.

TWENTY YEAR INDEX1981–2000

160 BOOK REVIEWS GEMS & GEMOLOGY SUMMER 2001

Ammolite 2: A Guide forGemmologists, Jewellersand LapidariesBy Donna Barnson, 116 pp., illus.,publ. by the author, 2000.Can$29.95*

At about the same time that I receivedthis book for review, my copy of theSpring 2001 issue of Gems & Gemo-logy appeared with its authoritativearticle on Ammolite by K. A. Mycha-luk, A. A. Levinson, and R. L. Hall.The contrast between the two publi-cations is striking, and in my viewfavors the article over the book despitethe latter’s larger size, its plethora ofillustrations, and its announced pur-pose to serve as a guide to Ammolite.It is not surprising that almost everyimportant fact covered in Ammolite 2is also covered in the article, since thebook was published first, but the arti-cle authors are more succinct in theirpresentation and provide greater geo-logical and mineralogical detail.

Ammolite 2, a large format (8.5 ´11 inches; 21.5 ´ 28 cm) soft coverbook, contains nearly 300 color photoillustrations, many of finishedAmmolite cabochons and jewelry. Itconsists of eight chapters covering thehistory of the industry, important per-sons connected with it, mining, pro-cessing, lapidary instructions, en-hancements, optical properties, colorand color patterns, and a grading sys-tem for finished stones. The gradingsystem is based on a combination ofcolor hue, quality, and the kind of pat-tern shown by the finished Ammo-lite. It is summarized by small colorphotos arranged according to grade onone side of a flap that folds inwardfrom the back cover; a series of perfo-rations allow the user to detach these

illustrations and use them separatelyfor grading purposes. Color photos arepresent throughout the book anddepict not only dozens of cut stonesbut also jewelry items, mining scenes,lapidary work, the mines and miningcountry, and persons connected withthe industry. On the whole, the colorquality is excellent, especially wherecut gems are concerned.

Concluding the book are a glossaryand a bibliography that both requirereworking for the next edition. Theglossary contains far too many terms,especially ones that are so commonthat any reader should know them(e.g., centimeter, class, gemstone,etc.). The “bibliography” is no morethan a listing of books and articles,without paginations, and in the case ofjournal articles, without volume,issue, or page numbers. Misspellingsare present throughout the book.

Ammolite 2 contains much inter-esting material and attractive colorphotographs. However, it suffers frompoor organization and inclusion ofmatter that could have been omittedentirely without serious loss (such asthe Indian legend “Iniskim,” whichsupposedly refers to a fetish madefrom Ammolite; a description of themosasaur, a prehistoric aquatic beastthat is said to have dined on ammo-nites; and the glossary). Above all, themanuscript should have been submit-ted to an expert editor, who presum-ably would have eliminated awkwardstatements, purplish prose, abruptchanges in writing style, redundan-cies, and misspellings.

From a gemologist’s standpoint,the article in Gems & Gemology saysit all. Nevertheless, Ammolite 2 offersa popular overview plus a host ofexcellent color illustrations and con-

siderable local color. It is a desirableaddition to any gemological library.

JOHN SINKANKASPeri Lithon Books

San Diego, California

The Dorling KindersleyHandbook of GemstonesBy Cally Hall, with photography byHarry Taylor, 160 pp., illus., publ.by Dorling Kindersley, London,2000. US$18.95*

Gemstones promotes itself as a recog-nition guide “for beginners and estab-lished enthusiasts alike” that “enablesyou to recognize each gemstoneinstantly.” Although instant recogni-tion may not be possible (or advisable),this smart-looking book provides agood start.

Inside are more than 800 full-colorphotographs of some 130 materialsused in jewelry. The Introduction con-tains short sections on sources, prop-erties, and synthetic gems, as well as akey to gems that occur in each of thedifferent colors. It is followed by chap-ters on Precious Metals, Cut Stones,and Organic Gems; then a table ofproperties, a glossary, and an index.

One advantage of Gemstones is thenumerous photos that provide rough,cut, and set illustrations for each gemmaterial. Another is its ease of use,especially for the layperson. Unlike

2001Book REVIEWS

EDITORSSusan B. JohnsonJana E. Miyahira-Smith

*This book is available for pur-chase through the GIA Bookstore,5345 Armada Drive, Carlsbad, CA92008. Telephone: (800) 421-7250,ext. 4200; outside the U.S. (760)603-4200. Fax: (760) 603-4266.

BOOK REVIEWS GEMS & GEMOLOGY SUMMER 2001 161

most handbooks, the photos areshown on the same pages as the text.Bordering the photos and text in table-like form are the “vitals”: R.I., S.G.,luster, etc. The binding and materialsused are of high quality, giving thisbook the feel of a rugged field guide.

Nevertheless, there are weakness-es. The book’s “vivid, full-color pho-tographs” tend to lack color satura-tion. Much of the information in theIntroduction sections (e.g., SyntheticGemstones) lacks detail, and innac-curacies occasionally appear. A clus-ter of albite crystals is used to depictdistinct cleavage, and parti-coloredtourmaline is misrepresented as thewatermelon variety. Adularescence,which is caused by the scattering oflight, is wrongly attributed to inter-ference. A quartz perfume bottle firstis described as having rutile inclu-sions, but later is presented correctlyas having black needles of tourma-line. Some high-tech treatments,such as diffusion, are not includedunder enhancements. The PreciousMetals chapter asserts that “althoughnuggets had been set in rings before1920, most platinum jewelry datesfrom this time.” However, this state-ment overlooks the fact that manyEdwardian pieces, which predate1920, were made of platinum. In theCut Stone chapter, sphalerite is statedas showing doubled back facets, yet itis singly refractive. Chile, not Argen-tina, is a source of fine lapis lazuli.The irritant causing natural pearl for-mation is usually a parasitic animalinstead of a piece of grit. The state-ment that Japan leads the world inthe production of cultured pearls is nolonger true, as China now occupiesthat position.

Gemstones is worthwhile despitesuch mistakes. It will be helpful par-ticularly to the novice gemologist,and even advanced enthusiasts willgain some knowledge. Be careful,though: You can’t do it all with thisbook alone! Good gemstone identifi-cation skills take considerable study,time, and practice to master.

MICHAEL EVANSGemological Institute of America

Carlsbad, California

Gem & Jewelry Pocket GuideBy Renee Newman, 156 pp., illus.,publ. by International JewelryPublications, Los Angeles, 2001.US$11.95*

Picture yourself sitting in a deck chairon a cruise ship, or settling in for along plane ride to some foreign desti-nation. As part of your trip, you planto buy a gemstone or piece of jewelry,so you are reading up on the subject.You would have a difficult time find-ing a better general reference on thesubject than this book.

The author draws from her exten-sive experience as a gemologist, tourdirector, world traveler, and author ofnumerous other gem- and jewelry-buying guides to produce a concise,detailed, and interesting guide. Throughthe use of over 100 color photographs,numerous black-and-white photos, linedrawings, and charts, she featuresdozens of different varieties of gem-stones with separate sections forAlexandrite and Cat’s Eye (Chryso-beryl); Amethyst and Other QuartzGems; Chalcedony; Emerald, Aqua-marine and Other Beryls; Garnet;Iolite; Jade; Kunzite; Lapis; Malachite;Moonstone and Other Feldspars;Opal; Peridot; Ruby and Sapphire;Spinel; Tanzanite; Topaz; Tourmaline;Turquoise; and Zircon. Additionalchapters profile diamonds and gemsfrom living organisms (pearl, amber,coral, and ivory). Other gemstone-spe-cific information is provided in chap-ters on price factors for colored gems,gem lab documents, notable gemsources, synthetic and imitationgems, and gemstone treatments (withinformation on stability, frequency,and acceptability of various treat-ments). Not every gem mentioned hasan accompanying photograph, but allare well described.

For those interested in purchasinga finished piece of jewelry, there arechapters on gold and platinum jewel-ry, jewelry craftsmanship, and how tohave jewelry custom-made. Metalsfineness markings, types of mount-ings, and care and cleaning tips alsoare included.

A subject that is not often covered

in books on gemstones and jewelry isthe set of factors that a buyer shouldknow to make a smart and safe pur-chase decision. These factors are cov-ered throughout the book, and thereare specific chapters on choosing ajeweler, finding a good buy, makingthe purchase, and selecting an ap-praiser. Another excellent chapter onthis subject covers Customs consider-ations, including regulations, U.S.duty rates on jewelry and gems, andtips on how to avoid problems.

It’s sometimes said that a littleknowledge can be a dangerous thing.This book certainly doesn’t replacegemological training and trade experi-ence, but it goes a long way in helpinggem and jewelry consumers makebetter buying decisions.

The size and readability of thisbook make it a “perfect fit” for itsintended use, and you’re likely to seeit being put to use in just about anypart of the world.

DOUGLAS KENNEDYGemological Institute of America


Nature Guide to Gemstones &Minerals of AustraliaBy Lin Sutherland and GayleWebb, 128 pp., illus., publ. by ReedNew Holland Publishers, Sydney,2000. Aus$24.95

This small—6 × 8 inches (15 × 21cm)—soft cover book is one of a seriesof Nature Guides published inAustralia. It is well bound and printedon glossy paper. The book succeeds inpresenting to the general reader themajor gems and minerals that occurin Australia. The first part of the book,What Are Gemstones & Minerals,gives a succinct summary of crystal-lography and physical properties. Thesecond, larger part, Guide to Gem-stones & Minerals, discusses eachgem and mineral in a well-written andeasy style. It mentions many varia-tions in color and shape, along withareas where these different materialshave been found, but it only touchesbriefly on geology and origin. The sizeof the book prevents the inclusion of

detailed maps and descriptions oflocalities, but the last page shows asmall-scale map of Australia on whichthe major areas are marked. The mainstrength of the book is the many pho-tographs, which, although small—1.5to 2 × 2.5 inches (4 to 5 × 6 cm)—dis-play the gemstones and minerals insharp detail and true color.

Text and photographs for eachgem and mineral group occupy twopages, except for opal (six pages) andsapphire (four pages). The book is agood introduction for the interestednature lover, but keen rockhoundsand amateur mineralogists will findthe presentation of the subject mattera bit too superficial.

A. J. A. (BRAM) JANSEArchon Exploration Pty. Ltd.

Carine, Western Australia

The Practical Guide toJewelry AppraisingBy Cos Altobelli, 292 pp., publ. bythe American Gem Society, LasVegas, NV, 2000. US$49.95*

This book presents a comprehensiveoutline of the appraisal profession’sbody of knowledge. It touches oneverything an appraiser needs toknow, but it also invites its readers toseek more comprehensive informa-tion on many of its subjects. Forinstance, the section on gemstoneswill encourage appraisers to expandtheir gemological knowledge, and thesection on pricing invites the apprais-er to establish personal trade sourcesand supplement their knowledge fromthe periodicals cited. All appraisersshould add to the “time lines” sectionas the industry evolves.

The Case Histories chapter isespecially interesting. It providesexamples and pointers for handlingjewelry and talking to clients. The

examples are highly relevant to situa-tions that an appraiser may encoun-ter. The situations mentioned in thecase histories should persuade theappraiser to research legal precedentsas well. The section on InsurancePolicies is an eye opener. Clientsshould be encouraged to use thedescribed points to talk to their insur-ance brokers regarding coverage.

Although the absence of an indexwas initially off-putting, I found theTable of Contents specific enough toserve as an index, if the reader hasworking knowledge of appraisal ter-minology. The forms and samplesincluded provide basic examples ofthe various materials necessary forappraisal purposes, but they alsoencourage appraisers to create theirown collateral documents.

This book challenges every jewel-er to understand the complexities ofthe appraisal profession, and serves asa guidepost to further independentstudies. Most instructional booksbecome static as soon as they are fin-ished. This one, however, involvesappraisers in the material and encour-ages them to add to its chapters as theindustry evolves.

The Practical Guide to JewelryAppraising reflects Cos Altobelli’sconsiderable experience as a jeweler,a gemologist and, especially, anappraiser. It belongs in the library ofevery serious appraiser.

GAIL BRETT LEVINEPublisher, Auction Market Resource

Rego Park, New York

OTHER BOOKS RECEIVEDEthnic Jewelry: From Africa, Europeand Asia, by Sibylle Jargstorf, 160 pp.,illus., publ. by Schiffer PublishingCo., Atglen, PA, 2000, US$29.95.*

This lavishly illustrated 8.5 × 11 inchsoft cover presents a wide range of eth-nic jewelry from several continents.The author combines the study of eth-nic and traditional folk costumes withthe jewelry of those cultures todemonstrate a holistic approach todecorative arts. In addition, by pre-senting an international variety ofethnic jewelry and traditional dress,she seeks to illustrate the similaritiesin approach that many cultures havetoward these art forms. The tradition-al jewels of Africa, Europe, and Asiaare covered in great detail with hun-dreds of photos and detailed descrip-tions. A price guide is included.

BARAK GREENGemological Institute of America


Costume Jewelers: The Golden Ageof Design, 3rd Ed., by Joanne DubbsBall, 205 pp., illus., publ. by SchifferPublishing Co., Atglen, PA, 2000,US$39.95.* All costume jewelry en-thusiasts should enjoy this heavilyillustrated, 8.5 × 11 inch hardback vol-ume, which focuses on the notablecostume jewelers of the 20th century.Christian Dior, Givenchy, “Coco”Chanel, and Hattie Carnegie are justsome of the more than 60 designersprofiled. Far from being consideredonly as cheap imitations, many piecesof costume jewelry have grown inpopularity and appreciation amongjewelers, collectors, and artisans.Unfortunately, along with an increasein appreciation comes an increase inunauthorized reproductions, whichthe author warns against in her newpreface. This revised edition also con-tains an updated pricing guide for allof the pieces shown.

BARAK GREENGemological Institute of America


162 BOOK REVIEWS GEMS & GEMOLOGY SUMMER 2001

COLORED STONES ANDORGANIC MATERIALSAchat [Agate]. extraLapis, No. 19, 2000, 96 pp. [in German]This issue in the special extraLapis series contains 15 articlesfrom 12 contributors, and is illustrated with superb color pho-tos. It is no surprise that about half the issue is dedicated to theagates of Idar-Oberstein, as these formed the basis of the Idar-Oberstein cutting industry. Several articles by R. Dröschel, U.Laarmann, and M. Henkel describe the geology of the Saar-Naheregion (which encompasses Idar-Oberstein), the special condi-tions required for the formation of agate, and the history anddevelopment of agate mining and the cutting industry (agatecutting was first mentioned in 1375 and probably did not occurin Roman times as is sometimes stated). J. Zang and A. Pethdescribe the two museums in Idar-Oberstein—DeutschesEdelsteinmuseum and Museum Idar-Oberstein—that displayimportant collections of agate and other gems.

The remaining articles cover general aspects of agates. R.Hochleitner attempts to answer the question “What is anagate?” and (with R. Dröschel, K. Fischer, M. Glas, and U. Henn)compiles a useful glossary of the numerous and sometimes puz-zling terms and names (some only in German) applied to chal-cedony. M. Glas and M. Landmesser discuss the current theorieson the formation of agate (e.g., SiO2 mobilization and accumu-lation). L. H. Conklin presents his curious collection of rareBrazilian eye agates, M. Glas tells the story of the Ptolemaios IIcameo (the most expensive agate in history), and G.Grundmann explains an almost forgotten printing techniqueusing agates (“Naturselbstdruck”). P. Jeckel describes new findsof agate made during the past decade. H. Zeitvogel demonstrateshow to cut and polish your own agates. RT

Gemological ABSTRACTS

2001EDITOR

A. A. LevinsonUniversity of Calgary

Calgary, Alberta, Canada

REVIEW BOARD

Anne M. BlumerBloomington, Illinois

Jo Ellen ColeGIA Museum Services, Carlsbad

R. A. HowieRoyal Holloway, University of London

Jeff LewisNew Orleans, Louisiana

Taijin LuGIA Research, Carlsbad

Wendi M. MayersonGIA Gem Trade Laboratory, New York

James E. ShigleyGIA Research, Carlsbad

Jana E. Miyahira-SmithGIA Education, Carlsbad

Kyaw Soe MoeGIA Gem Trade Laboratory, Carlsbad

Maha TannousGIA Gem Trade Laboratory, Carlsbad

Rolf Tatje Duisburg University, Germany

Lila TaylorSanta Barbara, California

Paige TullosGIA Gem Trade Laboratory, Carlsbad

Sharon WakefieldNorthwest Gem Lab, Boise, Idaho

June YorkGIA Gem Trade Laboratory, Carlsbad

Philip G. YorkGIA Education, Carlsbad

This section is designed to provide as complete a record as prac-tical of the recent literature on gems and gemology. Articles areselected for abstracting solely at the discretion of the section edi-tor and his reviewers, and space limitations may require that weinclude only those articles that we feel will be of greatest interest to our readership.

Requests for reprints of articles abstracted must be addressed tothe author or publisher of the original material.

The reviewer of each article is identified by his or her initials at theend of each abstract. Guest reviewers are identified by their fullnames. Opinions expressed in an abstract belong to the abstrac-ter and in no way reflect the position of Gems & Gemology or GIA.

© 2001 Gemological Institute of America

GEMOLOGICAL ABSTRACTS GEMS & GEMOLOGY SUMMER 2001 163

Approaches to improve cultured pearl formation in Pinc-tada margaritifera through use of relaxation, anti-septic application and incision closure during beadinsertion. J. H. Norton, J. S. Lucas, I. Turner, R. J.Mayer, and R. Newnham, Aquaculture, Vol. 184, No.1/2, 2000, pp. 1–17.

Cultured pearls from the black-lipped oyster Pinctadamargaritifera constitute a significant industry in theSouth Pacific, with current annual production fromFrench Polynesia and the Cook Islands at about US$117million and $2.6 million, respectively. The main prob-lems faced by pearl culturers from this region are post-operative oyster mortality, bead rejection, and poor-qual-ity cultured pearls.

This study was designed to determine the effectivenessof three techniques for improving the quality and quantityof round cultured pearls from P. margaritifera: (1) immer-sion of the oysters in a solution of propylene phenoxetol toinduce muscle relaxation before the bead is surgicallyimplanted; (2) disinfection of the operation site with adilute solution of povidone iodine; and (3) closure of thesurgical incision with a flexible cyanoacrylate adhesive.The study showed that although the relaxant lowered theincidence of bead rejection, it significantly increased theoyster mortality rate. Another adverse effect of the relaxantwas that the cultured pearls produced were lighter inweight due to reduced nacre secretion. The povidoneiodine antiseptic solution had no significant effect on mor-tality or bead rejection, and was the only treatment thatresulted in a lower percentage of total failures compared tothe controls. Oysters treated with the adhesive had highermortality and bead rejection rates, but this treatment didhave a positive effect on cultured pearl quality (i.e.,improved shape). The study also concluded that betterhygiene surrounding the beads and instruments wouldreduce cell inflammation and infection, thereby improvingcultured pearl production. MT

The history, geology, age, and fauna (mainly insects) ofBurmese amber, Myanmar. Bulletin of the NaturalHistory Museum (London), Geology Series, Vol. 56,No. 1, 2000, 83 pp.

This issue, devoted exclusively to Burmese amber (com-monly called Burmite), consists of 11 articles written by15 authors, most of whom are paleontologists from theRussian Academy of Sciences in Moscow and the NaturalHistory Museum in London. The first article, by V. V.Zherikhin and A. J. Ross, is a thorough overview of cur-rent knowledge based on an exhaustive literature search.Early Chinese literature suggests that Burmite has beenknown since the first century AD and soon thereafter wastraded in Yunnan Province. It was not mentioned inEuropean literature until 1613. The first visit by aWesterner to the Hukawng Valley—one of five knownBurmite-producing regions, but the only one that hasbeen commercially mined—was by Captain S. F. Hannay

in 1836. Subsequent visits by members of the GeologicalSurvey of India established that the amber occurs in sand-stones and shales of Middle Eocene age. The archaicinsects entrapped in the Burmite are assigned a probableCretaceous age, thus suggesting that the amber had beenreworked into the younger (Middle Eocene) sedimenthorizons.

The remaining 10 articles describe and tabulate theabundant fauna (mainly arthropods) found in Burmite.All the data reported in these articles are based on studiesof specimens in the extensive collection of the NaturalHistory Museum. Several new genera and species aredescribed for the first time. The fauna are well illustrated,some in color. As the value of amber is frequently influ-enced by the type, abundance, and quality of includedfauna, this issue will be of interest to amber collectorsand dealers alike. AAL

PIXE studies of emeralds. K. N. Yu, S. M. Tang, and T. S.Tay, X-Ray Spectrometry, Vol. 29, 2000, pp. 267–278.

This study attempts to identify chemical characteristicsthat will separate natural from synthetic emeralds andalso distinguish their source (i.e., geographic or manu-facturer). Fifty-six natural emeralds (from Colombia,Pakistan, Zambia, and Brazil) and 26 synthetic emeralds(both flux-grown and hydrothermal, from eight manu-facturers), all faceted, were analyzed nondestructively for33 elements by PIXE (proton-induced X-ray emission).

Although the chemical characteristics of the emeraldssometimes varied significantly for a single locality ormanufacturer, certain generalizations were possible. Theconcentrations of three elements—Cr, V, and Fe—enabled the distinction of Pakistani emeralds, as well asflux-grown synthetic emeralds from Chatham, Gilson,Taiwan, and Lennix. No single element, or combinationof a small number (< 4) of elements, gave satisfactoryresults for the other samples. When a larger number ofelement concentrations were analyzed by principal com-ponent analysis (PCA), an advanced statistical technique,unequivocal identifications were possible. With PCA, theseparation of all the natural emeralds from their synthet-ic counterparts was achieved. The technique also enabledthe identification of country of origin of all the naturalemeralds, as well as the manufacturers of most of the syn-thetic emeralds—only Russian flux-grown and hydro-thermal synthetic emeralds could not be distinguished bythis technique. PGY

SEM study on jadeite jade. X. Liu, Kuangwu Yanshi[Journal of Mineralogy and Petrology], Vol. 21, No. 1,2001, pp. 5–7 [in Chinese with English abstract].

The mineral composition, grain size, and microstructuralfeatures of the green part of a specimen of jadeite werestudied by scanning electron microscopy, and the varia-tions in scattering and intensity of color were correlatedwith grain size. Images of the cleavage planes show that


they are not smooth, but rather are characterized by lin-ear and “sawtooth” cleavage steps. RAH

La traçabilité des émeraudes: Une avancée décisive obtenuepar microscopie infrarouge (mmIRTF) [Tracing the ori-gin of emeralds: Decisive progress obtained byinfrared microscopy]. A. Cheilletz, P. de Donato, andO. Barrès, Revue de Gemmologie, No. 141/142, 2001,pp. 81–83 [in French].

A new Fourier transform infrared (FTIR) spectroscopytechnique has been applied to emeralds. This nonde-structive “micro-FTIR” method acquires high-qualitydata more rapidly than other techniques, and uses anadapter that produces a small (10 micron) IR beam for tak-ing high-resolution spectra. The distinction between nat-ural and synthetic hydrothermal emeralds is made bydetecting and interpreting the high-resolution FTIR pat-terns of water and CO2 in the samples; the latter compo-nent is characteristic of natural emeralds. For naturalemeralds, a database of 262 FTIR spectra representing 45deposits in 15 countries has been assembled, along withoxygen isotope data (d18O) and abundances for such ele-ments as Cr and V. According to the authors, takentogether these data enable the determination of geo-graphic origin. This is possible because emeralds havecharacteristic chemical, isotopic, and FTIR spectral vari-ations, which result in part from interactions betweenthe host rocks and hydrothermal fluids in the geologicenvironments in which they crystallized. MT

DIAMONDSDiamond Facts 2000/01—NWT Diamond Industry Report.

Northwest Territories Resources, Wildlife andEconomic Development, 2001, 22 pp.

This year (2001) is the 10th anniversary of the first dia-mond discovery in the Northwest Territories (NWT),Canada, and the region has quickly become recognized asa world-class diamond producer. Highlights of activities inthe NWT are presented in this informative, well-illustrat-ed booklet prepared by the government agency responsiblefor economic development. Topics include: a timeline ofimportant events (e.g., discoveries, approval of environ-mental reviews, and start of production at the Ekati mine);general information on the world diamond industry, withCanada’s current and potential future positions; currentexploration activities in the NWT; descriptions and statusof advanced diamond mining projects; and the role of theGovernment of the Northwest Territories (GNWT) in var-ious aspects of the diamond industry (e.g., certification ofselected diamonds as mined, cut, and polished in theNWT, and sold as Canadian Arctic™ diamonds).

This booklet emphasizes—with an opening messagefrom the Minister of Resources, Wildlife and EconomicDevelopment—that the GNWT is committed to maxi-mizing the development of natural resources (includingdiamonds) and to adding value to Canada’s diamonds. In

addition to creating job opportunities at the mines, post-production value-added opportunities are visualized inthe form of increased employment in the cutting sector,establishment of grading facilities, jewelry manufactur-ing, and using NWT diamonds for tourism-related activi-ties. A complimentary copy of this booklet may berequested by e-mailing [email protected].

AAL

Etching of diamond crystals in a dry silicate melt at high P-T parameters. V. M. Sonin, E. I. Zhimulev, I. I.Fedorov, A. A. Tomilenko, and A. I. Chepurov,Geochemistry International, Vol. 39, No. 3, 2001,pp. 268–274.

Most natural diamond crystals have been subjected todissolution processes that result in morphological andetch features such as curved faces and edges, and trigons.The authors investigated such dissolution processesusing both natural and synthetic diamond crystals. Thesamples were placed in a silicate melt (corresponding tothe chemical composition of an alkali basalt) at high pres-sure and high temperature, to approximate the conditionsexperienced by natural diamonds.

Various morphological and etch figures were pro-duced, some very similar to those found in natural dia-monds, depending on the experimental conditions. Threetypes were distinguished:

1. Positive trigons (with edges oriented parallel to theedges of the octahedral faces) and {hhl} surfaces withparallel striations normal to the initial octahedraledges were observed in samples subjected to relativelylow pressures and in experiments with silicate meltsin contact with air.

2. Negative trigons (with edges oriented opposite tothose of the octahedral faces), or hexagonal etch pitsand {hhl} surfaces with striations parallel to the initialoctahedral edges, occurred only at high pressures.

3. Negative trigons or hexagonal etch pits and {hhl},{hk0}, and {hkl} surfaces formed only in high-pressureexperiments.

In all cases, the dissolution rate increased withincreasing H2O in the experimental systems. TL

Isotope dating of diamonds. D. G. Pearson and S. B. Shirey,in D. Lambert and J. Ruiz, Eds., Application ofIsotopes to Understanding Mineralizing Processes,Reviews in Economic Geology, Vol. 12, Chap. 6,1999, pp. 143–171.

The need to know the ages of diamonds is driven by bothscientific curiosity and economic necessity. For example,such information should enable scientists to determinewhether diamonds formed continuously throughout theearth’s history or during discrete episodes. Moreover, dia-mond ages may be of value in determining new targetareas for primary deposits and also in constraining the


sources of alluvial diamonds. Determining ages directlyby isotopic methods, however, is not possible because thediamond lattice contains no useful radioisotope. The onlyreliable method of dating diamonds is based on the iso-topic analysis of their mineral inclusions, which is thesubject of this critical review.

The mineral inclusions used for diamond dating mustbe syngenetic (i.e., formed at the same time as the dia-mond). Criteria are given for recognizing such inclusions.The specific radioisotope system employed generallydepends on the nature of the inclusion: Sm-Nd for garnetand clinopyroxenes, Re-Os or Pb-Pb for sulfides, and Ar-Arfor clinopyroxene. Interpretation of the results is often dif-ficult, and many factors must be considered. Conflictingresults occasionally are obtained by different methods.Everything involved with the isotopic dating of diamonds,from the isolation of an appropriate inclusion to the oper-ation of the complicated instruments (e.g., mass spec-trometers), requires great care and is time consuming.

When all published isotopic diamond ages determinedsince the mid-1980s are summarized, a wide variety ofcrystallization ages are evident, but the vast majority aregreater than 1 billion years. AAL

A new approach to the exploration of diamond deposits bylarge-diameter boreholes. V. V. Krotkov, DokladyEarth Sciences, Vol. 373A, No. 6, 2000, pp. 930–932.

This article describes the application of a large-diameter (4m) drilling technique for sampling kimberlite ore at theLomonosov diamond deposit in the Arkhangelsk provinceof Russia. The drilling technique could extract an averageof 2.58 tons/hour of kimberlite to a depth of 240 m with-out serious complications. The ability to extract such alarge volume of material rapidly and efficiently enhancesproductivity in sampling diamondiferous rock with lowdiamond content (but possibly high-quality rough). Thetechnique reduces the time needed to obtain the necessaryvolume of kimberlite for estimating ore grade, while itminimizes worker exposure to underground working con-ditions. Repair and maintenance costs are also minimized,and the drill can function at low temperatures (to -38°C).

Joshua Sheby

The source of the Espinhaço diamonds: Evidences fromSHRIMP U-Pb zircon ages of the Sopa Conglom-erate and Pb-Pb zircon evaporation ages of metavol-canic rocks. M. L. de Sá Carneiro Chaves, T. M.Dussin, and Y. Sano, Revista Brasileira de Geo-ciências, Vol. 30, No. 2, 2000, pp. 265–269.

Alluvial diamonds are hosted by the Sopa Conglomerate,which outcrops in the Diamantina region of the EspinhaçoRange in Minas Gerais, Brazil. The original source of thesediamonds has never been established. One suggestion isthat the diamonds might be derived from associatedmetavolcanic rocks. Using a Sensitive High Resolution IonMicroprobe (SHRIMP), the authors determined radiomet-ric ages for different isotopes (e.g., 238U/206Pb, 207Pb/206Pb) in

zircons separated from both the Sopa Conglomerate andthe metavolcanics. The results showed multiple ages (e.g.,3.6, 2.8, 2.0 billion years) for the zircons from the SopaConglomerate, all of which were older than the zirconsfrom the metavolcanics (1.7 billion years). Because themetavolcanics are younger than the Sopa Conglomerate,they could not have been the source of the Espinhaço dia-monds; hence, the origin of these diamonds remainsunknown. PGY

Surface properties of diamonds in kimberlites [sic] process-ing. V. Chanturiya, V. Zuev, E. Trofimova, Y. Dikov,V. Bogachev, and G. Dvoichenkova, Proceedings ofthe XXI International Mineral Processing Congress,Rome, Italy, 2000, pp. B8b-9–B8b-16.

The use of grease table and froth flotation procedures inthe recovery of diamonds from kimberlite ore may resultin significant losses, particularly for certain size fractions.The explanation lies in the variable nature of the surfacesof rough diamonds, due to surface characteristics. Someare hydrophilic (have a strong affinity to water), whereasothers are hydrophobic (water repellent); the former canbe recovered with water-based flotation methods, where-as the latter adhere to grease and are recoverable on agrease table.

Using samples from the Mir pipe in Russia, theauthors identified differences in the disparate nature ofrough diamond surfaces. Hydrophilic surfaces are coveredwith a layer of CO2 gas molecules and HCO3 radicals(both of which originate from carbonate minerals in thekimberlite) as well as minerals of the serpentine group. Incontrast, hydrophobic surfaces have superficial films ofcarbonate minerals and minerals of the talc group. Atechnique patented in Russia (No. 2071836), based on theuse of an anolyte (an acid product of water electrolysis),modifies the diamond surface so that recovery losses canbe reduced by a factor of 1.5–2.0. AAL

United States diamond market: Analysis of polished dia-mond consumption 1994–2000. E. Cohen, MazalU’Bracha, Vol. 15, No. 129, January 2001, pp. 45–48.

From 1994 through 2000, the importation (which can beequated with consumption) of polished diamonds intothe U.S. increased rather uniformly on an annual basis interms of both wholesale value and carat weight. Duringthis period, there was a 132% increase in value (fromUS$4.94 to $11.44 billion), and a 91% increase in weight(from 10.70 to 20.47 million carats). The greater increasein polished value compared to weight indicates increas-ing demand in the U.S. for higher-quality and largerstones during that time period.

In 2000, the three main suppliers of polished dia-monds imported into the U.S. as a percentage of totalvalue were Israel (47%), India (23%), and Belgium (21%).By weight, however, India was the predominant supplier,accounting for 62% of the imports; Israel and Belgiumsupplied significantly less (19% and 10%, respectively).

166 GEMOLOGICAL ABSTRACTS GEMS & GEMOLOGY SUMMER 2001

From 1994 through 2000, the average per-carat value ofall sizes of polished diamonds imported into the U.S.increased by a modest 21% (from $462 to $559 per carat);this is explained by the fact that the value of diamondsimported from India remained essentially static ($198 percarat in 1994 compared to $202 in 2000) throughout thisseven-year period. In 2000, the average per-carat values ofpolished diamonds imported from Israel and Belgiumwere $1,359 and $1,142, respectively. AAL

GEM LOCALITIESThe Alto Ligonha pegmatites—Mozambique. M. B. Dias

and W. E. Wilson, Mineralogical Record, Vol. 31,No. 6, 2000, pp. 459–497.

The Alto Ligonha pegmatite district of northernMozambique is significant to mineralogists and gemolo-gists for the quality and variety of gems and minerals ithas produced. This comprehensive article provides a his-tory (political and exploration) of the region starting atthe end of the 19th century, a summary (with maps) ofthe geology of the district, and a table of the most impor-tant mines (organized into 27 groups, each comprisingone-to-six individual pegmatites) together with the mostnotable gems or minerals found at each. From the 1930sthrough the 1970s, the district was an important produc-er of gem-quality tourmaline and beryl, as well as topazand spodumene. Many rare and economically importantore minerals (of tantalum, beryllium, and lithium) alsowere mined. Production during the 1980s and 1990s suf-fered because of political problems, but mining activitiesare being encouraged by the current government.

The pegmatites are difficult to prospect because vege-tation and lateritic soil cover the area, but they are local-ly revealed by prominent quartz cores or concentrationsof mica in the soil. Although hundreds of pegmatite bod-ies have been mined, they probably represent only a smallfraction of the district’s potential. The Muiane pegmatite,which measures 400 m wide and 1 km long, is perhapsthe most important producer of mineral specimens.

The bulk of the article is an alphabetical listing andbrief description (including chemical and physical proper-ties) of the 77 minerals reported from the district. Thissection is illustrated with superb color photographs of gemand mineral specimens, as well as crystal drawings ofselected minerals. A most unusual, and fascinating, fea-ture of this article is the final section, “Memoirs of AltoLigonha,” which contains reminiscences by the seniorauthor of his tenure as a geologist, most of it in AltoLigonha, from the mid-1930s until the end of thePortuguese colonial period (1975). JEC

Die Pegmatite von Alto Ligonha in Nord-Mozambique[The pegmatites of Alto Ligonha in northernMozambique]. P. Schäfer and T. Arlt, Lapis, Vol. 25,No. 8, 2000, pp. 13–17, 54.

For decades, Alto Ligonha has produced several pegmatite

gem minerals—sometimes in giant crystals. Most of thepegmatites are deeply weathered, so there is little need forexplosives. Many of the dumps and old pits are beingreworked for overlooked gem crystals.

The authors describe their visit to Muiane, the mostimportant gem mining area, which is dangerous andwhere bribes are a way of life. They also visited severalsmaller and less dangerous areas, including the beryl andemerald deposit Maria III at Niame. Because the localmining industry is focused on cuttable material, manypieces of broken gems were offered; it was nearly impos-sible for the authors to obtain undamaged gem crystals ormineral specimens. RT

Classification and mineralization potential of the peg-matites of the Eastern Brazilian Pegmatite Province.G. Morteani, C. Preinfalk, and A. H. Horn,Mineralium Deposita, Vol. 35, 2000, pp. 638–655.

The Eastern Brazilian Pegmatite Province (EBPP) encom-passes the pegmatite districts of Itambé, Araçuaí, Safira,Nova Era, Aimorés, and Espera Feliz, almost all of whichare important sources of gems, especially fine tourma-line, aquamarine, and morganite, as well as Li, Sn, Nb,and Ta ore minerals. All of the districts except Itambé aresituated in fold belts surrounding the eastern border ofthe São Francisco craton, and were formed during theBrasiliano tectonothermal event (~600 My) in host rocksthat show decreasing grades of metamorphism from eastto west. The one exception, the Itambé district, is locatedwithin the São Francisco craton, and is of Transamazonicage (~1,900 million years [My]).

To determine the degree of fractionation of the EBPPpegmatites and assess their mineralization potential,major- and trace-element analyses were obtained for 530K-feldspar and 550 muscovite samples. A wide variety ofcompositions were recorded, from slightly fractionedmuscovite-class pegmatites to highly fractioned peg-matites of the rare-element class. Districts with thewidest range in pegmatite fractionation (such as Araçuaíand Safira) are also leaders in the production of gem andrare-element minerals. Emeralds are more likely to befound in Be- and Li-pegmatites of Transamazonic age (i.e.,the Itambé district). Within the EBPP, a correlation seemsto exist between grade of metamorphism, degree of frac-tionation, and mineralization of gems and rare-elementminerals. The use of geochemical indicators (e.g., plottingCs vs. K/Rb for K-feldspar or muscovite) appears usefulfor targeting highly fractionated pegmatites and evaluat-ing their mineralization potential. RT

Emerald mineralisation in Colombia: Fluid chemistryand the role of brine mixing. D. A. Banks, G. Giuli-ani, B. W. D. Yardley, and A. Cheilletz, MineraliumDeposita, Vol. 35, 2000, pp. 699–713.

It is generally accepted that Colombian emeralds in boththe eastern (Gachalá, Chivor, and Macanal) and western(Peñas Blancas, Muzo, Coscuez, and Yacopi) mining dis-


tricts formed from the interaction of hypersaline brineswith the host black shales and evaporites. The purpose ofthis study was to quantify the composition of these flu-ids, which were extracted from inclusions in emeralds,calcite, dolomite, quartz, and fluorite by a bulk crush-leach technique and subsequently analyzed by differentspectroscopic methods (ICP-AES, FES, and GFAAS).

In contrast to fluids from the other minerals, those inthe emeralds (fluid 1) are dominated by Na and Cl andhave the lowest concentrations of all other elements.While a range of origins has been proposed for high-salin-ity brines—with seawater as the most common—theauthors found that in both districts, all the fluid inclu-sions in emeralds have Cl:Br ratios much greater thanthat of seawater. Therefore, they believe the fluids to bethe result of halite dissolution, most probably from thelocal salt beds. The authors also postulate an origin underlow-grade metamorphic conditions.

The fluids from quartz inclusions (fluid 2) are of simi-lar salinity and contain less Na, but significant amounts ofCa, K, Fe, and Cl. Inasmuch as the fluid compositions inboth the western and eastern zones are similar, they seemto be controlled by interaction with the local host rocks,which in both cases are black shales and evaporites. Theauthors suggest that in certain conditions, beryllium mayhave been leached from wall rocks and introduced intofluid 1. Subsequently, a mixing of both fluids caused pre-cipitation of fluorite and parisite, the destabilization of Be-F complexes, and the growth of emeralds. RT

Emeralds in Greenstone belts: The case of Sandawana,Zimbabwe. J. C. Zwaan and J. L. R. Touret, MünchnerGeologische Hefte, Series A, Vol. 28, 2000, pp.245–258.

Most emeralds occur in “schist-type” deposits (Colom-bian emeralds are a notable exception), which are com-monly attributed to the interaction of pegmatitic fluidswith Cr-bearing host rocks (e.g., metavolcanics and/orultramafics). This interaction is usually envisaged as asingle-stage contact-metasomatic event, with the emer-alds occurring at or close to the border of the pegmatiticveins. However, based on regional and detailed geologicstudies, as well as geochemical and mineralogical data,this origin is not appropriate for emeralds in the MwezaGreenstone belt, such as at Sandawana, even though theyare normally found very near the contact between green-schists and pegmatites.

The pegmatitic bodies at Sandawana are completelyaltered (albitized), and are strongly folded and sheared alongwith their greenstone host rocks. The gem-quality emer-alds occur in strongly foliated schists at least 1 mm awayfrom the pegmatites, in relatively low pressure areas called“traps.” The authors suggest that the emeralds formed dur-ing folding, shearing, and regional metamorphism, from apegmatitic fluid rich in F, P, Be, and Li that invaded the con-tact zones and incorporated various other elements (e.g.,Cr) necessary for the formation of emerald. KSM

Edelsteine aus Sambia—Teil 2: Turmalin und Aquamarin[Gemstones from Zambia—Part 2: Tourmaline andaquamarine]. C. C. Milisenda, V. Malango, and K. C.Taupitz, Zeitschrift der Deutschen Gemmolo-gischen Gesellschaft, Vol. 49, No. 1, 2000, pp. 31–48[in German with English abstract].

The important Jagoda pegmatite mining area in Zambiais a source of gem-quality pink, red, and green tourma-lines, as well as aquamarine. Geologic descriptions andmaps are presented for several of the pegmatites (e.g.,Jagoda, Muchinga, and Pela). The gemological propertiesof the tourmaline and aquamarine are typical. The tour-maline is characterized by inclusions of “trichites” (hair-like capillaries) and growth tubes; the aquamarine hasminute fluid inclusions.

These pegmatites are unusual because gem-qualitytourmaline and aquamarine rarely occur together in thesame deposit, even though both generally form near thecores of zoned pegmatites that are enriched in alkali- andrare-elements. Thus, a special set of growth conditions isrequired. The Jagoda pegmatites probably formed by themobilization of fluids during the Pan African metamor-phic event (650–450 million years ago), when they wereemplaced as relatively thin stratabound bodies into meta-morphic host rocks. They apparently did not form in themore usual way, that is, by magmatic differentiation fromgranitic melts. AAL

The Rist and Ellis tracts, Hiddenite, North Carolina. D. L.Brown and W. E. Wilson, Mineralogical Record,Vol. 32, No. 2, 2001, pp. 129–140.

This article reviews the history, geology, and productionof the Rist and Ellis gem tracts, near Hiddenite, NorthCarolina. Although this area is known primarily for theproduction of emerald and hiddenite (bright green Cr-bearing spodumene), excellent specimens of other miner-als also have been mined, including monazite, muscovite,quartz (smoky and amethyst), rutile, tourmaline (schorl),and xenotime.

Two amateur mineralogists, J. A. D. Stephenson andW. E. Hidden, discovered the mineralized pegmatites andhydrothermal veins in the area in 1875 and 1880, respec-tively. After decades of intermittent mining and severalchanges in ownership, the area was acquired in 1969 by apartnership of Warren Baltzley and Charles Rist, whichoperated through 1981 as American Gems Inc. Duringthis period, the adjacent Rist and Ellis tracts were openedto the public for collecting on a daily fee basis. There areno records of the amount or quality of production duringthis time, but it is generally known that many fine-qual-ity specimens were obtained. In 1969, for example, a 59 ctemerald crystal was found and later cut into a 13.14 ctgem, the “Carolina Emerald,” which now resides in theNew York showroom of Tiffany & Co.

Since 1982, ownership of the properties has changedthree times, and numerous other stunning specimenshave been discovered. These include North America’s


largest emerald crystal (1,686.3 ct), still unnamed, whichwas found in 1984.

All the important minerals found at this famous local-ity are described in varying detail, with their typical crys-tal habit and mode of occurrence noted. Excellent full-color photographs accompany the text. JEC

The São Geraldo do Araguaia opal deposit, Pará, Brazil.T. A. Collyer and B. Kotschoubey, Revista Brasileirade Geociências, Vol. 30, No. 2, 2000, pp. 251–255.

The recently discovered opal deposit near São Geraldo doAraguaia, in the state of Pará, contains several types ofopal, the main ones being “precious” opal (showing play-of-color; called “noble” opal by the authors), “jasper” (red-dish) opal, and fire opal. All occur as fracture fillings,veins, and/or local accumulations within biotite schist ofthe Xambioa Formation. The opal-bearing zone is approx-imately 3 km long and up to 6 m thick.

Inclusions within the opal consist mainly of frag-ments of metamorphic minerals from the host rock,including kyanite and biotite; the latter has been partial-ly altered to chlorite. Other included materials are quartzgrains, acicular rutile crystals (with a roughly radial, fan-like habit), and hematite.

It is likely that most of the opal formed as a result oflow-temperature hydrothermal activity and tectonism dur-ing Jurassic and Cretaceous time, which was associatedwith the opening of the Atlantic Ocean. Hydrothermalprocesses mobilized silica at depth within the earth’s crust,and this was subsequently precipitated as opal near the sur-face. A later episode of opal deposition probably wasresponsible for the formation of the precious opal. LT

JEWELRY MANUFACTURINGFancy free. A. Skuratowicz and J. Nash, American Jewelry

Manufacturer, March 2001, pp. 72–74, 76, 78, 80–82.Setting a fancy-shaped gemstone (e.g., a marquise cut)may pose problems that require the skill of an experi-enced jeweler. Complications can arise from a stone’sshape and its durability under stress (at the points of amarquise, sharp corners, curved sides), variations in thecut (uneven girdle, pavilion bulge), and its inherent prop-erties (toughness, cleavage, hardness, types of inclusions,susceptibility to thermal shock, and sensitivity to harshchemicals).

After taking into consideration artistic preferencesand a stone’s shape and characteristics, a jeweler can thenchoose the elements of a setting: style and metal type.Setting style is determined by the stone’s durability andthe location of pressure points. Different metal types offervarying degrees of malleability and durability dependingon the alloy components; a soft malleable alloy, whetherprecious or nonprecious, usually works best.

Given the problems inherent in working with fancycuts, the jeweler may have to make some adjustments atthe bench. Some suggestions include annealing hard

metal alloys, laying out and measuring pieces beforebeginning, and compensating for pressure points withadditional burring. Joshua Sheby

PRECIOUS METALSHard 22 carat [karat] gold alloy. C. Cretu, E. Van Der

Lingen, and L. Glaner, Gold Technology, No. 29,2000, pp. 25–29.

Market demand for high-karat gold jewelry is growing,especially in India and the Middle East. Unfortunately,high-karat gold lacks the hardness of lower-karat gold.Mintek, a South African company, has developed a 22Kgold alloy with a hardness near that of 18K gold; evengreater hardness can be attained by a combination of coldworking and heat treating of the metal. Tests conductedby Mintek show that the alloy is similar in color to 22Kgold, can be cast using conventional methods, and resiststarnish and corrosion as much as 22K gold. It also canundergo in excess of 99.99% cold rolling without inter-mediate heating and cracking. Solder testing revealedvery good hardness, even greater than that of 22K gold.Standard equipment and techniques can be used with thealloy. Although the other elemental constituents of thealloy are not revealed, the authors state that no hazardouselements are used during its manufacture. PT

Rise in shine. American Jewelry Manufacturer, Vol. 45,June 2000, p. 33.

Seeking a tarnish-free silver, British silversmith PeterJohns added germanium to the alloy formula. Still con-sidered sterling (at 92.5% silver), the alloy is tarnish resis-tant and also does not develop firescale (an inorganic sub-stance that develops after cooling). Kultakeskus Oy, a sil-ver manufacturing company in Finland, partnered withJohns because this alloy saves production time. The alloyis conducive to laser welding, and its manufacture ismore environmentally friendly than those processes thatuse acids and other substances to prevent firescale.Although the alloy resists tarnish, it does develop a yel-low coating that is easily removed. Other reported draw-backs include its higher price and limited availability.

PT

SYNTHETICS AND SIMULANTSCharacterization of Verneuil red corundum by X-ray

topography. C. Rinaudo and P. Orione, MaterialsChemistry and Physics, Vol. 66, 2000, pp. 143–148.

Over 90% of the synthetic corundum currently producedworldwide is grown by the Verneuil flame-fusion process.Boules grown by this method tend to crack along theirlength at the end of the growth process. To explain thisphenomenon, the authors analyzed cross-wise andlength-wise slices (~1 mm thick) obtained from Verneuilsynthetic corundum boules. Optical microscopy, energy-dispersive spectrometry, and X-ray transmission topogra-


phy were used to characterize the samples. Particularemphasis was placed on detecting differences in the crys-tallographic, physical, and chemical characteristics of theslices relative to their position and orientation within aboule. Only the bottom portion of the boules, corre-sponding to the initial growth stages, are composed ofsingle crystals. From the middle of the boule upward, thereis considerable stress-related deformation (easily observedas intense interference colors with crossed polars), whichleads to a macromosaic structure.

The authors attribute boule cracking to the loss ofmonocrystallinity accompanied by stress in the middleand upper parts of the boule, which corresponds to thelatter stages of the growth process. It is suggested that thearea of the boule closest to the flame during initial growthundergoes a type of annealing that results in improvedcrystal quality. MT

Graphite ®®diamond transition under high pressure: Akinetic approach. J. Sung, Journal of MaterialsScience, Vol. 35, 2000, pp. 6041–6054.

This article reviews the kinetics (i.e., rate) of the graphite-to-diamond transition under high pressure and the effec-tiveness of various solvent-catalysts (i.e., Fe-Ni, Cu,CaCO3, P) that can facilitate the process. Two types oftransitions are recognized: direct and solvent-assisted.The direct transition occurs without a catalyst, and thetemperature of the transition appears to depend on thedegree of structural perfection (i.e., polytype composition)of the original graphite. The more “perfect” the graphite,the lower the temperature at which it may transform todiamond.

The effectiveness of various catalysts is discussed, andsome disputes are reviewed. The authors conclude thatthe more carbon a solvent can dissolve at ambient pres-sure, the more effective it will be as a catalyst for the tran-sition of graphite to diamond at high pressure. Hence, Feor Ni are more powerful catalysts than Cu, which is morepowerful than P or CaCO3. Wuyi Wang

Simulated diamond gemstones formed of aluminum ni-tride and aluminum nitride: Silicon carbide alloys.C. E. Hunter, WO Document No. 00/22204 A2,April 20, 2000; U.S. Patent No. 6,048,813, April 11,2000.

Diamond-like colorless synthetic gems can be producedby growing and faceting single crystals of pure aluminumnitride (AlN), or an alloy of aluminum nitride and siliconcarbide (SiC—synthetic moissanite). Alloys in the com-positional range of AlN(0.8):SiC(0.2) to AlN(0.5):SiC(0.5)are preferred. Several dopants (gallium, cerium, gadolini-um, and samarium are mentioned) can be added to growcrystals of a desired color. The crystals can be grown byseveral techniques, and various aspects of the growth pro-cedures are described in detail; the fashioning process isalso mentioned. However, gemological and physical prop-

erties (e.g., refractive indices, dispersion, spectra, hardness,specific gravity) are not given other than the statementthat the refractive indices of pure AlN and the alloys arecomparable to those of diamond. The U.S. patent may beviewed at http://www.uspto.gov/patft/index.html.

Karl Schmetzer

Spectroscopic properties of coloured, synthetic corun-dums and spinels produced in Skawina. M. Czaja,Mineralogica Polonica, Vol. 31, No. 1, 2000, pp.55–68.

Electronic absorption, excitation, and luminescence spec-tra are presented for synthetic a-Al2O3 (corundum with atrigonal structure), synthetic a-Al2O3 (does not occur nat-urally; does not have a trigonal structure), and syntheticspinels of various colors grown at the Research andDevelopment Laboratories of the Aluminum Plant atSkawina, near Craców (Kraków), Poland. Different crystalgrowth orientations, concentrations of impurity ions, andthe presence of more than one chromophore were estab-lished as the main reasons for the variations in color. Allof the colored spinel varieties were found to be non-stoi-chiometric, with an MgO:Al2O3 ratio of 1:2.6. The resultsindicate tetrahedral coordination of Co2+ in the syntheticspinels and Mn2+ in synthetic a-Al2O3. RAH

TREATMENTSGübelin Gem Lab introduces thermal enhancement scale.

G. Roskin, Jewelers’ Circular Keystone, Vol. 171,No. 11, 2000, pp. 52, 54.

The thermal processes used to enhance the color andappearance of gem corundum are varied, as are theireffects. The stones may be heat treated either before orafter cutting, with or without chemicals (e.g., borax).Vitreous byproducts of melted chemicals (“glass”), aswell as vitreous products of natural inclusions, mayresult from the heating process. All laboratories will indi-cate whether a stone has been heat treated; some will alsoestimate how much glass remains, while others will useonly such qualitative terms as minor, moderate, or pre-dominant.

The Gübelin Gem Lab in Lucerne, Switzerland, hasdeveloped and initiated a new six-point thermal enhance-ment (TE) disclosure system to characterize and classifythe entire range of heat-induced features in gem corun-dum; master stones are used for comparison. TE1, forexample, indicates only minute traces of residue insidepartially “healed” fractures. Conversely, a treated stonedesignated as TE6 shows large glass-filled cavities, inaddition to healed fractures with droplets of residue. Thesystem explains what the thermal enhancement hasachieved, rather than attempting to quantify the amountof enhancement. It is hoped that with full disclosure ofheat treatments and their effects, consumer confidencewill return. AAL


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