Product Guide The Difference Between Opal Doublets and Triplets If like us, you're a longstanding lover of opals, then you've likely already learned to differentiate between natural and synthetic opals. A true fanatic might even know about an opal's Australian or Ethiopian origins. However, when it comes to the difference between opal doublets and triplets, there still seems to be some confusion. Doublets consist of two distinct layers -- a black backing and a thin slice of opal. The material of the backing varies, though is most typically made of industrial glass. The thin slice of opal utilize in doublets is also usually thicker than that used in triplets. On the other hand, triplets consist of three distinct layers -- a black backing, a thin slice of opal, and an additional dome-shaped cap, most often made of clear glass. Because triplets possess thinner slices of opal than doublets, this third added layer creates a cabochon on top, magnifying and protecting the opal in the process. Both doublets and triplets consist of synthetic opal slices, relying on the black backing to give the illusion of a solid black opal stone while keeping costs affordable for those in the market for opals.