Choudhary G. (2004) Are treatments only for natural stones, Midlands Focus, 5^th issue, pp 16-18

The author discusses various types of treatments which are being performed on synthetic gem materials like diamond, rubies, sapphires, emerald, opal, etc.

Revised in 2014 in two parts

Fernandes S. Khan M. & Choudhary G. (2003) A compilation of infrared absorption spectra of some specific gemstones – as an aid to their identification, Australian Gemmologist, 21, 321-327

In the recent past, there has been a growing need for reliable techniques of gemstone identification. This paper presents a compilation of infra red absorption spectra for specific gemstones, all of which appear similar in colour but otherwise display distinct properties. Using the transmission mode of FTIR spectrometer, about 25 samples of each gem species examined were recorded, keeping in mind the variation that anisotropic gem minerals have in optical properties with orientation. The basic objective of this compilation of IR spectra was to provide 'fingerprint' absorption patterns that permit separation of gemstones of similar colour from each other and, in some cases, natural gemstones from synthetics. No attempt was made to specify the causes for the absorption bands observed. The major transmission and absorption regions and characteristic peaks in the IR spectrum of the gemstones investigated for this report are presented both in spectral and tabular form.