How are opals made?

Opals are made up from tiny uniformed spheres (balls) of transparent hard silica, which fit together in an orderly three dimensional frame (left diagram). It is the orderliness of the spheres that separates the precious opal from the common opal. These tiny spheres also determine colours and patterns of opals. read more

Opals are found naturally and made synthetically. Opals come in a variety of types from common opals, which are opals that lack color, to opals that have a myriad of colors in their make up to solid red opals known as fire opals. read more

Opals too thin to produce a "solid" may be combined with other materials to form attractive gems. An opal doublet consists of a relatively thin layer of precious opal, backed by a layer of dark-colored material, most commonly ironstone, dark or black common opal (potch), onyx, or obsidian. read more