FTIR, gemology, gems

External reflectance infrared spectroscopy permits a very rapid and nondestructive determination of the species of a mineral. It is particularly useful with polished gems in that it requires no more than plac-ing the stone, loose or mounted, on a reflection de-vice in the infrared spectrometer and observing the recorded spectrum. Therefore, compared to the classi-cal methods of physical measurement such as refrac-tive index, specific gravity, and the like, reflectance spectroscopy provides a much faster means of estab-lishing the species of the gem and, in some cases, whether it is natural or synthetic.