What is Synthetic Opal?

As the name would suggest, synthetic opal is man-made opal. The confusion, driven by marketing, is caused by simulated opal, a much cheaper and easier to produce substitute.

Simulated opal can be thought of as similar to glass or plastic gemstones. They are made mostly of resin (typically 80%), with silica to provide a simulation of the colour and fire that natural opal displays.

Synthetic opal conversely is more comparable to lab grown industrial gemstones, like ruby laser foci or sapphire watch faces. They replicate the chemical makeup of their natural counterparts, but being grown in a lab environment allows control of the details of the composition. Generally a synthetic opal replicates the nominal 80% silica of natural opal, with resin making up the remainder; but in higher end synthetics water is used, perfectly replicating natural opal chemically, but allowing a near infinite array of colours not possible in natural opal.