(term used throughout the opal industry) A thin layer of precious opal, onto one face of which is fixed an opaque base of natural or artificial material. Onto the other face is fixed a clear, domed top to magnify and also protect the opal. The better quality triplets have a clear quartz top, others a clear plastic top. Triplets can make use of very thin slices of precious opal which would otherwise be wasted.

An opal triplet is a manufactured stone that is composed of three thin layers that are glued together. A thin layer of opal is sandwiched between a layer of clear quartz and a layer of either obsidian or ironstone. The clear quartz is the top layer, making the gem harder (and less susceptible to scratches). An opal triplet is an opal doublet with a quartz layer on top. Triplets must be cleaned very carefully.