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In gemology, Raman spectroscopy is a very useful means not only for gemstone identification, but also because it can be used for the identification of gemstone treatments, which is subject of the present paper. The treatment of emerald fissures with oil and other natural substances to enhance their clarity has been performed for many centuries. Nowadays, emeréld fillers also comprise various artificial resins, mainly epoxy resins. Because of the different behavior of these new substances in the stone, the gemstone trade require an identification. This can be performed successfully with Raman spectroscopy, and examples are given. Waxes and resins are also used to impregnate jadeite and other porous stones. Traditionally, these treatments are detected with infrared spectroscopy, but it is shown that Raman spectroscopy is also able to detect such treatments.The newest gemstone treatment concerns brownish diamonds of type ha. These can be improved to near colorless by an enhancement process developed by General Electric, USA, using high temperature and pressure. A comparison of Raman spectroscopic features in the visible area (luminescence bands) of both treated and untreated colorless diamonds is given.Finally, examples of artificially colored pearls and corals and their detection with Raman spectroscopy are shown.

This preliminary study focuses on using secondary ion mass spectrometry (SIMS) to measure relative carbon isotope ratios for natural and synthetic diamonds (i.e. those grown by both chemical vapour deposition [CVD] and high-pressure, high-temperature [HPHT] techniques). The synthetic diamonds (of both CVD and HPHT origin) had significantly lower relative carbon isotope values than the natural diamonds. The lowest value was obtained for the CVD synthetic diamond sample, in agreement with results from other investigators. More research is desirable on the carbon isotope variation of synthetic diamonds.