A very common technique used to display Opals and Ammolite.
This is a technique used to fuse two materials together. One of its more common uses today is with Opals, where two are fused together to achieve more depth in the gem. While this is widely accepted in the jewellery industry, the seller should always disclose whether the gem is a doublet, as it is far less valuable than a single piece of Opal.
The doublet technique is easily identifiable in a loose gemstone where when viewed from the side you will often witness bands. It is a lot more difficult to spot in a gem which has already been set into jewellery. If you are offered a cheap Opal ring and the seller tells you that you should not get Opals wet, he is probably referring to the glue that has been used to bond the layers together!
A triplet is produced in the same way as a doublet, but has three layers. Again, when talking of Opals, it is normally the middle layer that is the genuine gem. Boulder Opal consists of fine layers of natural Opal which have formed naturally on ironstone rock: it is removed from its host rock while being cut, and placed back onto it, much like how gem-quality Ammolite is produced. For most Boulder Opals the finished gem is actually a doublet or triplet opal.
