Natural Diamonds, Sri Lankan Sapphire, Vietnamese Ruby (All Photographs by Tino Hammid)

GemPen® Filters (Courtesy of Gemometrics)

World Gem Foundation

GemPen® Test Results - Diamonds, Blue Sapphires & Rubies

Natural and Lab-created DiamondsGemstone Filter Number of Stones Tested Fluorescence % Fluorescence Range % Fluorescence Range % Phosphorescence %

Natural Colourless Diamonds 1 161 161 100% Faint to Low 94.5% Strong to Very Strong 5.5% 10 6%Natural Diamonds (Yellowish to Brownish) 1 82 82 100% Faint to Low 100% Strong to Very Strong 0% 32 39%

HPHT Lab-created Diamonds 1 11 11 100% Faint to Low 0% Strong to Very Strong 100% 11 100%CVD Lab-created Diamonds 1 21 21 100% Faint to Low 0% Strong to Very Strong 100% 18 86%

Natural and Lab-created Blue SapphiresGemstone Filter Number of Stones Tested Fluorescence % Fluorescence Range % Fluorescence Range % Phosphorescence %

Natural Blue Sapphires 2 26 3 11.5% Inert 88.5% Strong (Chalky) 11.5% 0 0%Natural Blue Sapphires 3 26 3 11.5% Inert 88.5% Faint to Low 11.5% 0 0%

Flame-fusion Lab-created Blue Sapphires 2 17 17 100% Inert 0% Medium to Strong 100% 0 0%Flame-fusion Lab-created Blue Sapphires 3 17 17 100% Inert 0% Medium to Strong 100% 0 0%

Flux-Melt Lab-created Blue Sapphires 2 3 1 33% Inert 67% Low 33% 0 0%Flux-Melt Lab-created Blue Sapphires 3 3 1 33% Inert 67% Faint 33% 0 0%

Natural and Lab-created RubiesGemstone Filter Number of Stones Tested Fluorescence % Fluorescence Range % Fluorescence Range % Phosphorescence %

Natural Rubies 4 26 7 27% Inert 73% Faint to Low 27% 0 0%Flame-fusion Lab-created Rubies 4 18 18 100% Inert 0% Strong to Very Strong 100% 0 0%

Flux-Melt (Knischka) Lab-created Rubies 4 7 7 100% Inert 0% Low to Very Strong 100% 0 0%Flux-Melt (Chatham) Lab-created Rubies 4 6 6 100% Inert 0% Strong to Very Strong 100% 0 0%

CONCLUSIONS

Diamonds While all of the natural and lab-created diamonds tested at IGE (El Instituto Gemológico Español) with the assistance of Egor Gavrilenko fluoresced using the GemPen®, the majority of the natural diamonds (94.5%) exhibited faint to low fluorescence while 100% of the HPHT and CVD diamonds exhibited strong to very strong fluorescence. Interestingly of the 161 colourless natural diamonds tested, only 6% exhibited phosphorescence while 100% of the HPHT diamonds and 86% of the CVD diamonds phosphoresced. Phosphorescence however in lower coloured diamonds (not fancy colours) was higher (39%). This means that of the 243 natural diamonds tested, 17.3% would give a result that would warrant a closer examination while of the 32 lab-created diamonds tested, 9.3% of the stones would need to be tested further.

Blue Sapphires

Only 11.5% of the natural blue sapphires exhibited fluorescence using the GemPen ® while 100% of the flame-fusion (Verneuil) lab-created blue sapphires fluoresced. We found that the reactions were stronger under Filter Two compared to Filter Three. None of the stones tested (natural or lab-created) exhibited any phosphorescence. While unfortunately only three flux-melt ‘Chatham’ blue sapphires were tested, we did not find the results conclusive.

Rubies

Only 27% of the natural rubies exhibited faint to weak fluorescence using the GemPen ®. In the lab-created rubies, 100% of the flame-fusion (Verneuil) lab-created rubies exhibited strong to very strong fluorescence while of the thirteen flux-melt (Knischka & Chatham) lab-created rubies tested, twelve exhibited strong to very strong fluorescence and one (Knischka) exhibited weaker fluorescence that we felt could potentially be confused with that seen in the natural rubies. None of the stones tested (natural or lab-created) exhibited any phosphorescence. In our opinion, these results combined with a microscopic examination of the stones would be very useful in confirming the ‘synthetic’ origin of the stones.