Non-destructive spectroscopic methods for gem analysis: A short review

Since antiquity, gems fascinated worldwide cultures, being used for adorning jewels or precious objects. Gems analysis primarily aims to determine identity, origin (natural or synthetic) and geographic or geological source of a gem, which in turn define its value. In view of preciousness and rarity of gems, their analysis requires the use of non-destructive or micro-destructive methods, some of which might be limited when gems are mounted in jewels. Beside traditional gemological tools and laboratory instruments, portable/mobile analytical methods are especially useful to study gems in jewelry collections or to characterize gems in field. Portable Raman spectroscopy emerged as a powerful technique in gems analysis; it allows a rapid identification of a gem, providing also insights on other relevant aspects for its classification; however, origin and provenance can be only hypothesized through the analysis of solid and fluid inclusions by laboratory apparatus. The determination of trace-element chemistry by using portable X-ray fluorescence might overpass this limit, providing the chemical fingerprint of the geological and geographical origin of a gem. In some cases, advanced and micro-destructive analytical techniques enable more precise and certain gem classification. This short review intends to provide an overview on the potential of non-invasive and non-destructive complementary spectroscopic methods useful for studying inorganic and organic gemological materials.