What are doublets and triplets?
A separate category of opals are the partially artificial stones known as doublets and triplets, modified opals backed by a backing and covered with a resin layer. In short, these stones are very thin slices of natural opal glued to a black backing, thus very successfully imitating the spectacular appearance of black opal.
Gluing a slice of opal to a black backing makes its colour much darker and richer. However, doublets and triplets are generally much cheaper than solid black opals as they only contain a small amount of actual opal. A true opal with the same appearance as a triplet can be ten times the price, which is why triplets can make beautiful jewelry with dark opals affordable. You need to be aware of what you are buying, and it is equally important to take proper care of doublets and triplets to prevent water damage, which can cause the backing to peel off.
As doublets and triplets, various mosaics are made from tiny slices of precious opal.