corundum, color.4, synthetic corundum.7, gems

Laboratory irradiation has been used to change or develop color in many gem materials. Examples include the development of yellow in beryl, pink-to-red in tourmaline, blue in topaz, brown (the “smoky” color) in quartz, and various colors in diamond. (For more information, see K. Nassau’s comprehensive Gemstone Enhancement, 2nd ed., 1994, Butterworth/Heinemann, Oxford, England, and C. E. Ashbaugh’s “Gemstone Irradiation and Radioactivity,” Gems & Gemology, Winter 1988, pp. 196–213.)