Golecha C. (2006) Diffusion-treated synthetic sapphire, Gems & Gemology, Vol. 42, No. 2, pp 185 -186

The author describes the identification features of a diffusion-treated synthetic sapphire, which includes presence of gas bubbles and plato-lines. The specimen had a healed fracture which made the identification challenging.

Choudhary G. & Golecha C. (2006) Diffusion treated synthetic sapphire with unusual fluorescence, Gems & Gemology, Vol. 42, No. 4, pp 287- 289

The specimen had a blotchy colour appearance similar to that often seen in sapphires subjected to diffusion treatment. When exposed to short-wave UV radiation, the specimen showed a strong patchy chalky fluorescence that followed the facet pattern. When we compared the colour concentrations to the fluorescence reaction, it was clear that only the facets lacking colour reacted to short-wave radiation; those portions showing colour concentrations were inert. The sample was identified as synthetic on the basis of plato lines. This pattern was probably caused by "over polishing" of the star and upper girdle facets after the diffusion treatment, which removed the inert shallow colouration and exposed the untreated, colourless sapphire portion that fluoresced to short-wave UV.

Choudhary G. & Golecha C. (2006) Circular ring-like inclusions in a diffusion –treated sapphire, Gems & Gemology, Vol. 42, No.4, pp 286-287

The sapphire displayed patchy colouration indicating diffusion treatment. Presence of straight and hexagonal milky zones indicated natural origin. The stone displayed an interesting feature when viewed with magnification and illuminated with a fibre optic light; groups and rows of circular rings composed of fine white particles. Such inclusions are common features of beryllium-treated corundum. However, these may be found in traditionally heated corundum exposed to very high temperatures. In this sample, presence of beryllium could not be tested, therefore, it was simply identified as diffusion treated.

Choudhary G. (2006) Unusual composites, Midlands Focus, 9^th issue, pp 19 – 22

Composites are made to imitate well-known gem materials, like emerald and corundum, to improve the overall appearance of a gem or to provide durability for a specific gem like opal. At the Gem Testing Laboratory, Jaipur, we tested few composites with unusual patterns or features. The stones were probably not made to imitate any particular material but simply to produce fancy gems. These composites mainly consisted layers with coloured metallic coatings on the inner surface