![Opal Doublet/Triplet Examples.](https://www.langantiques.com/university/wp-content/uploads/2017/08/Opal-doublet-triplet.jpg)
A triplet is a kind of composite stone that combines three parts. A good example is the opal triplet which often is an ironstone backing dressed with a slice of precious opal that is covered by a crystal cabochon. In this way, the opal is protected by wear and tear by the dome, and its jewelry life is prolonged.