Doublet and triplet gemstones

A doublet is a gemstone assembled from two parts. A triplet has three layers, sometimes two stone sections separated by coloured cement. The components may be natural or manmade. These names describe construction rather than a particular mineral species.

Opal and other combinations

An opal doublet may join a thin slice of opal to a backing. An opal triplet adds a transparent cap, for example quartz or glass. Assembled gems can also combine other materials. GIA has documented doublets of synthetic spinel and synthetic sapphire. An assembled stone is therefore not necessarily wholly natural or wholly artificial.

Examination and care

Look for joins from the side and ask for the layers to be described when buying. A closed setting can hinder inspection; do not remove the stone yourself. Prolonged contact with water can weaken adhesive in opal doublets and triplets. Establish the construction before cleaning and do not describe an assembled gem as a single solid stone.

Sources: GIA, Assembled Stones; GIA, Synthetic Sapphire and Synthetic Spinel Doublets; Australian Government, Cut and polish opal doublets and triplets; GIA, Opal care and cleaning.