true doublet

A true doublet is a type of assembled gem, meaning it's a cut jewel made from two or three pieces of stone cemented together to appear as a single, more valuable stone. In a true doublet, both pieces are of the same material. These gems are typically constructed by joining two pieces at the girdle, which is the widest part of the stone.1

True doublets can be identified by immersing them in a liquid with a refractive index similar to the gem fragments. The cement layer will appear as a dark line, revealing the construction. This method helps distinguish them from false doublets, where the crown and pavilion are made of different materials, or imitation doublets, which are entirely made of glass but presented as more valuable.1