Feature Gems & Gemology, Fall 1981, Vol. 17, No. 3

Cryogenics, an Aid to Gemstone Testing

Cooling of gemstones to low temperatures provides for enhanced detail in the absorption spectra. This article identifies some simple techniques for cooling gems that are available to the jeweler-gemologist and offers a detailed description of the procedures used in the research laboratory for automatic recording of spectra at low temperatures. Examples of the differences observed between spectra recorded on stones held at room temperature and those recorded for the same stones at significantly lower temperatures are presented for diamond, emerald, and synthetic alexandrite.