opal

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,…

Opal triplet: Australian rough, ceramic base, and quartz top (30 x 23 mm). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Black Opal, Australia, position #2, (stone in ring approximately 10 cts). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Black Opal, Australia, position #1, (stone in ring approximately 10 cts). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Slovakian opal on matrix. Photo by Slovakiaopal. Licensed under CC By-SA 4.0.

Australian opal rings. Photo by Jessica Rabbit’s Flickr. Licensed under CC By 2.0. (Cropped to show detail).

Opal, 88 cts, 4.1 x 2.2 x 1.7 cm, Ethiopia. © Rob Lavinsky, www.iRocks.com. Used with permission.

41.3-ct boulder opal in a gold and diamond mounting. © Opal Auctions. Used with permission.

René-Jules Lalique (1860–1945), a well-known Art Nouveau designer of the Edwardian era, incorporated opals into his jewelry pieces, like…