gems, advanced testing, cathodoluminescence, CL

Gem materials containing activator ions or structural defects luminesce in an electron beam and reveal features not visible to the eye when using ordinary light. This phenomenon called cathodoluminescence (CL) has been known in diamonds for nearly 100 years. The technique has only recently been resurrected by mineralogists as a fallout from the development of the electron microprobe analyzer. Results obtained so far promise versatile possibilities of applications to gemology and the jewelry trade, especially when coupled to a scanning micro-spectrophotometer. This technique can produce luminescent colors and spectra useful in research which in turn can be used to detect and identify gem materials, show crystal structural defects not observed by other means, separate natural, synthetic, and imitation gemstones, exhibit zoning, detect certain dyes and enhancement processes, and be used by the prospector, miner, sorter, cutter, and gem synthesizer in separations, sorting and quality control functions. The structural and compositional variations reveal potential genetic implications.