The veins of opal displaying the play of color are often quite thin. This problem has given rise to unusual methods of preparing the stone as a gemstone.

An opal doublet is a thin layer of opal, backed by a mineral such as basalt, ironstone or obsidian. The dark background emphasizes and transforms the play of colors into a more attractive display.

Combined with modern techniques of polishing, doublet opal can produce similar effect as the black opal or boulder opal. But it costs a mere fraction of their price. Doublet opal has the genuine opal layer at the top – visible and touchable. But this is not the case with triple cut opal.

The triplet-cut opal has the colored material as a dark background and has a domed cap of clear quartz or plastic on top. This can take a high polish and act as a protective layer for the opal. The top layer also acts as a lens, magnifying to emphasizing the play of color of the opal of lower quality placed beneath it.

Triplet opals therefore have a more artificial appearance, and are not classed as precious opal.