Imitation gemstones are most commonly found antique jewelry in the form of gemstone doublets and triplets, which are composite stones. Composite stones are jewelry pieces comprised of more than one stone bonded together.

Gemstone doublets
Gemstone doublets were first used in antique jewelry but are making a comeback. There are two types of gemstone doublets - the true doublet and the false doublet.

True gemstone doublets are created using two genuine gemstones and then bonding them together to form a single, larger gemstone of better color than the originals. For example, using two pale green emeralds with a deep green glue will create a larger, more intense green composite stone.

False gemstone doublets consist of a thin slab of gemstone that is glued on top of a colored glass bottom to form a large composite gemstone. Soude emeralds are a false gemstone doublet that consists of a colorless spinel top and bottom pieces fused together with a green bonding agent.

Gemstone triplets
Gemstone triplets were first used in antique opal jewelry..

See other names for fake gemstones for a list of names and materials used.