True Colors
Color stability testing reveals interesting color gains
By Deborah A. Yonick
During routine color stability testing of sapphires, experts at the Gemological Institute of America (GIA) in Carlsbad, California, observed an unusual gain of orange or yellow coloration to a padparadscha-like color or even to pure orange. These latest observations underscore how identifying and reporting the color of some sapphires continues to challenge gemologists, stone dealers, and jewelers.