Choudhary G. (2010) Various chatoyant stones - an overview, Midlands Focus, 17th issue, pp 15 - 17

Chatoyancy is one of the most common optical effects observed in many gemstones, as a result of presence of elongated inclusions arranged in one direction with the stone being cut with a curved surface (example, cabochon). The most widely used and well known gemstone exhibiting this optical effect is a chrysoberyl, however as mentioned above, it can be present in any stone, provided it has the prerequisites. Some of the other gemstones exhibiting this phenomena and commonly available on the gem market include apatite, diopside, opal, quartz, scapolite and sillimanite, which are only few to name. This article provides an overview of these mentioned cat’s eye gemstones. This however, does not provide a hardcore technical data and a thorough analysis, but it though gives an insight and a comparative look of various types of cat’s eyes in these gems.

Choudhary G. (2010) New types of glass- with deceptive crystalline inclusions, Midlands Focus, 15^th issue, pp 3-5

Few translucent blue and green specimens were studied, which turned out to be glasses. Visually, they imitated blue chalcedony and / or turquoise. Glass imitation chalcedonies or turquoise have been known in the past as well, but these specimens were quite unusual because of their inclusion patterns; these consisted of transparent elongated ‘crystalline inclusions’. Some of these were scattered while some were densely packed and gave an impression of devitrification effect commonly observed in glasses. These numerous elongated crystals were quite similar to the actinolite / tremolite needles found in emeralds of Russian and /or Sandawana origin. When observed under crossed-polar, these elongated inclusions appeared birefringent giving interference colours.

Choudhary G. (2010) Another interesting composite – diamonds and rock crystal, Gems & Jewellery, Vol. 19, No. 3, pp 12 – 13

The submitted specimen was colourless, triangular in shape, reminiscent of a curved ‘macle’. The sample was submitted to us as a rough diamond. The preliminary observations were enough to identify the specimen as composite. It consisted of fine chips or flat crystals of rough diamond stuck to the surface of a colourless material, fashioned as curved triangular pyramid/tetrahedron. This was created mainly to imitate an aggregate crystal of diamond. The central colourless specimen was identified as natural rock crystal on the basis of bull's eye optic figure and infra red spectra.

Choudhary G. (2010) Glass imitations of emerald with straight zones, Gems & Gemology, Vol. 46, No. 2, pp 155-156

The Gem Testing Laboratory of Jaipur, India, received for identification the two green specimens (17.05 and 1.79 ct), which were submitted as emeralds. Although the stones’ appearance initially suggested emerald, their exceptional colour and clarity raised doubts regarding their origin. Striking features were observed with magnification. Both specimens displayed a series of sharp, straight lines along their lengths. Such straight lines are often associated with growth lines or zoning in natural gemstones. When viewed from different angles, some of these lines were revealed to be planes with sharp edges