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Being based in a gem centre like Jaipur, GTL is exposed to a range of unusual and bizarre gem materials submitted for identification. Because of the dedication and passion our staff gemmologists possess, these gem materials undergo a thorough research for their complete understanding. The results of such research are shared with the world through publications in various highly read gemmological journals of international repute.

In The Press


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Choudhary G. (2012) Green and orangy yellow calcite from Pakistan, Gems & Gemology, Vol. 48, No.3, pp 217-218

The author describes the properties of green and orangy yellow calcite recently discovered in marble quarry in Baluchistan province of Pakistan. The gemmological properties measured were typically associated with calcite; however, subtle banding was visible, caused due to fine acicular to fibrous crystals arranged in layers


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Choudhary G. (2012) Golden coral, Gems & Jewellery, Vol. 21, No.2, pp 12-13

The Gem Testing Laboratory, Jaipur received a bead of golden coral which was not only impregnated but also coated with a thick layer of polymer/ plastic. Classified as horny type, golden coral habitually belongs to the Antipatharian order, Stichopathes, Cirrhipathes, Leiopathes, but some may also belong to order Zoanthiniaria, species Gerardia and order Alcyonacea. In addition to the structural features typically displayed by the horny type corals, this specimen displayed numerous large gas bubbles present in cavities as well as in layer towards the surface, indicating coating.


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Choudhary G. (2012) Coated quartz imitation of rubellite tourmaline, Gems & Gemology, Vol. 48, No. 2, pp 154-155

A purplish pink sample fashioned as tumbled bead was brought to the author's attention by Kashish Sachdeva during the Jaipur Jewellery Show 2011. The bead's colour initially suggested rubellite tourmaline, but its dull lustre raised some suspicion of a coating. No features were readily visible to detect the presence of coating. Under desk model spectroscope, broad bands at around 580 and 650 nm was seen, indicating dye. Gemmological properties and absorption spectrum ruled out the possibility of tourmaline. Further microscopic examination with transmitted light revealed colour blotchiness and bleeding near some pits and cavities, evidence of surface related artificial colouration.


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Choudhary G. (2012) Dioptase from Mozambique, The Australian Gemmologist, Vol. 24, No.9, pp 215-219

One dark bluish green dioptase specimen weighing 8.88 carats was submitted to the Gem Testing Laboratory, Jaipur, India. The specimen was unusual for its size, crystal form, transparency and phantom-like growth. Dioptase, usually found as massive aggregates and druses on other minerals, was seen here as a single crystal of fairly good size. The specimen was reported to originate from Mozambique. IR spectra obtained by KBr method was very useful in the identification together with its gemmological properties. The specimen was dark bluish green, a colour typically associated with translucent emeralds exhibited under normal lighting/viewing conditions. However, under transmitted light, it displayed a much brighter green colour and a better degree of diaphaneity. IR spectra measured by KBr method displayed strikingly clear and distinct peaks in the region 4000 - 400cm-1. Major peaks were seen at around 3380 and 3260 cm-1 due to O-H vibrations; 1735, 1265, 1120, 993, 956, 887 and 781 cm-1 due to Si-O stretching; 628, 572, 516, 495 and 450 cm-1 due to Si-O bending


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