Light Opal comes from the South Australian fields of Mintabie, Coober Pedy and Andamooka, although the first material was mined in the state of New South Wales at White Cliffs (1887).
The commonly termed 'white opal' can be identified by a light body tone. Light opal is usually found in seams, unlike most other types of precious opal, allowing it to be cut into standard sizes, for use in commercial of jewellery.
This variety includes opal which is transparent or very translucent and in better qualities shows a distinct and very bright range and play of colours. Light crystal opal generally comes from South Australian opal fields.
Black crystal opal is found in the Lightning Ridge fields, this type has a smoky colouring, which the light crystal opal does not have.
Boulder opal is found in select areas of inland Queensland. The term boulder comes from the ironstone on which the layer of opal is formed, often giving the opal an uneven surface to further enhance the array of colours.
Opal is formed in narrow cavities of the ironstone, when split they often form what are called 'boulder pairs'.
Boulder matrix opal
This opal is mostly found in fields in far south western Queensland. The opal, over time has filled in the minute cavities and voids within the host rock (usually iron stone). Unlike regular Boulder Opal the host rock is part of the visual attraction of the stone, the blend of the opal and rock creates unique patterning, colour, and texture. The fields, from which Boulder Matrix Opal is sourced, have distinct differences in the appearance of the opal they produce.
Black opal could best be described as opal with a dark or black background colour. The face of the stone predominantly radiates hues of red, blue, green, and orange.
Lightning Ridge in New South Wales is the only place in the world where black opal is commercially mined.
A doublet from Opal House is a slice of precious light crystal opal that has been enhanced by bonding ironstone to the back. This gives the opal a black or boulder opal look. Doublets are made to enable people to enjoy the beauty of the precious opal at a more affordable price.
A doublet becomes a triplet when a clear quartz crystal is superimposed on an even thinner slice of opal. The protective crystal dome also helps to enhance the precious opal by magnifying its true colours. Triplets traditionally use a lower grade of opal than doublets, for this reason we do not use triplets in our jewellery.