For decades, milky whitish sapphires from Sri Lanka known as geudas were heated at a high temperature to produce superb blue colors. However, this process can also turn geudas into fine yellow and orange gems, such as this 3.60-ct specimen. Photo © Joel E. Arem, PhD, FGA. Used with permission.
Credit: Joel E. Arem, PhD, FGA
|Natural or man made||Natural|