gems, color science, color theory, causes of color in gems, physics of color

Advances in technology have significantly improved our ability to enhance the color of natural gemstones and to create synthetic counterparts, while parallel developments are being made to distinguish between natural and artificial colors, as well as natural and synthetic materials. This article explores contemporary methods used to modify gemstone color and highlights analytical techniques employed by laboratories at the California Institute of Technology to determine color origin. Examples discussed include dyed jade, synthetic turquoise, heat-treated beryl and zircon, irradiated spodumene, and topaz that has been both irradiated and heat treated to produce an attractive blue hue.