Choudhary G. (2010) A Be-diffused sapphire with interesting zoning patterns, Gems & Gemology, Vol. 46, No.1, pp70

One 2.16 ct brownish orange sapphire, notable for its zoning pattern was studied. With magnification, fine surface-reaching fingerprint-like inclusions were observed. Some had whitish bubble-like textures, such as those associated with high-temperature heat treatment, which suggested the presence of a foreign substance such as borax. Notably, fiber-optic lighting revealed a few zones of fine minute particles that formed nested patterns with unusual square/rectangular profiles, rather than the hexagonal or pseudohexagonal shapes that are expected in corundum. Since this sapphire’s colour suggested beryllium diffusion, we expected to see surface-conformal colour zoning. Immersion in methylene iodide in diffused lighting indeed revealed such colour layers. The colour zones were arranged in unusual concentric oval to cushion-shaped zones. In the absence of any other inclusion feature, the presence of the concentric coloured bands in this Be-diffused natural sapphire could lead to its misidentification by an inexperienced gemmologist as a flame-fusion synthetic.

Choudhary G. (2009) Dyed pink alabaster, Gems & Gemology, Vol. 45, No. 4, pp 309 - 310

A cabochon of alabaster was submitted to the Gem Testing Laboratory of Jaipur for identification, and it had an unexpected orangy pink colour and resembled chalcedony or opal because of its translucency. Sample's very low hardness (scratched by fingernail) and gemmological properties easily identified it as alabaster. Colour concentrations along the surface breaks and visible spectrum confirmed it as dyed.

Choudhary G. (2009) Synthetic sapphires with ‘natural-like’ sheen, Gems & Jewellery, Vol. 18, No. 3, pp 6-9

Synthetic gemstones displaying s features similar to those of their natural counterparts and vice versa are often encountered in the Gem Testing Laboratory in Jaipur. Gagan Choudhary describes a new type of synthetic sapphire displaying sheen effects similar to those seen in some natural sapphires. The stones tested were yellow, green and greenish blue, but other colours such as red (ruby) and blue are also available. In most stones, the sheen effect is visible at the table facet but in some it is also present as zones well within the stone. However, routine gem testing is sufficient to enable identification of these stones as synthetics.

Choudhary G. (2009) “Smoky” gray beryl, Gems & Gemology, Vol. 45, No.3, pp 216 – 217

The Gem Testing Laboratory in Jaipur, India, examined a 71.57 ct step-cut stone. It had a gray colour with moderate saturation and slightly brownish gray reflections near the corners; one of the corners showed relatively stronger reflections. When it was tilted in standard lighting against a white background, subtle zones of pale brown colour were observed at some angles. The colour appearance and brown zones were reminiscent of smoky quartz. Gemmological properties identified the specimen as beryl, which was unusual for its 'smoky' gray colour