Opal gems synthesized through a process created by Pierre Gilson appear very natural. Gilson opals: cabochons from 3 to 6 cts. Photo © Joel E. Arem, PhD, FGA. Used with permission.
Article: Opal Stones and Gems: Value, Price, and Jewelry Information
Credit: Joel E. Arem, PhD, FGA
|Natural or man made||Lab-made|