Choudhary G. (2009) Serpentine cat’s eye, Gems & Gemology, Vol. 45, No. 2, pp 151-152

The Gem Testing Laboratory in Jaipur, India, had the opportunity to examine an unusual opaque bluish green cabochon (36.63 ct) that had a broad but distinct chatoyant band. The colour, greasy-to-dull luster, and low heft suggested it was serpentine. Gemmological properties, infra red spectrum and EDXRF analysis concluded the cat's eye as serpentine. This gem variety however, commonly found as massive and is used as imitation for jadeite or nephrite, but encountering this gem variety as chatoyant was quite rare. Chatoyancy in this sample was caused due to thin parallel planes composed of fine films.

Fernandes S. & Choudhary G. (2009) Gem quality andalusite from Brazil, Gems & Gemology, Vol. 45, No. 2, pp 120-129

Widely known as a rock-forming mineral, andalusite is not frequently encountered as a gem material. This article documents the gemmological and spectroscopic properties of numerous rough and cut samples of gem-quality andalusite from Brazil. The colour varied from yellowish green and green to brownish pink (including bicoloured green and brownish pink), and some were faceted with the pleochroic colours attractively oriented. Transparent samples of the chiastolite variety of andalusite were particularly interesting. All the samples displayed a complex growth pattern, with the various inclusions oriented along the growth directions. Heat treatment produced subtle changes in colour, if any, but fracture filling with resin resulted in obvious improvements in apparent clarity.

Choudhary G. & Vyas M.B. (2009) ‘Multiphenomenal’ quartz from India, Gems & Jewellery, Vol. 18, No. 1, pp 10-12

The Gem Testing Laboratory of Jaipur, India, encountered yellow-green quartz, which displayed a strong chatoyant band as well as ‘ten-rayed’ asterism making this quartz specimen highly unusual. Asteriated quartz commonly originates from Sri Lanka, but this specimen was reportedly from the Kangayam–Karur belt in the state of Tamilnadu, India. The intersection point of this ten-rayed star was inclined at approximately 45° to the chatoyant band. At one particular angle, chatoyancy and asterism could be seen together, confirming that they are separate phenomena

Choudhary G. (2009) Interesting natural and synthetic spinels, Gems & Gemology, Vol. 45, No.1, pp 68-70

Two specimens of spinels displaying interesting inclusion scenes were studied; purplish pink and a pale grayish yellow. Gemmological properties of purplish pink sample indicted natural origin while of pale grayish yellow synthetic. Inclusion features in these spinels were notable. Natural spinel had kite-shaped domains forming lath like patterns, while the synthetic one displayed zones of minute pinpoints that formed sub-hexagonal pattern. This pattern also displayed bluish subtle zones. It is quite unusual to see sub-hexagonal zones in a gem belonging to the cubic system