Opal is unique for its mesmerising flash of rainbow colours that alternate in different lighting. This ‘play of colour’ is caused by the reflection of light from its completely random silica structure, meaning that no two opals ever appear the same. Opals contain a comparatively large amount of water within their structure, as they are result of seasonal rains and silica. Opals can have a range of ‘body’ colours, to include white, blue, colourless, black, and transparent. Their play of colour is kaleidoscopic, and is dependant upon the size of the silica spheres within. One particular variety of opal is the ‘fire opal’ and is transparent to translucent reddish orange.

Opal is the birthstone for October, and is gifted for thirty-four year wedding anniversaries. The Greeks thought that opals gave the gift of prophecy as a result of their mystical colour play. Opals are primarily sourced from Australia, but have also been found in Brazil, Canada, Germany, Ethiopia, Honduras, Hungary, Indonesia, Mexico, Spain and the USA.