Outback Gems of Australia - Australian Opal

Australian Opal

DESCRIPTION OF TYPES OF OPAL

A Solid

An opal which is all opal. It can be precious opal with a potch or common opal base, or, precious opal on an ironstone base as is the case with boulder opal. A distinction is made between natural (opal which is naturally formed in the ground and mined, as one piece) and synthetic (opal which is man made, often made by the companies such as Gilson Laboratories).

Doublet Laminate

In the past, man made doublets were common. As the value of opal increased, the making of doublets decreased and there are very few manufacturers of doublets these days. The most likely sighting of a doublet will be in an old ring and the common practice at that time was to set it in a bezel or rubbed in setting. Old doublets were usually attached to good black opal potch or snowflake obsidian. There are a number of boulder opal doublets on the market made from thin Coober Pedy opal. Ironstone is crushed and mixed with epoxy resin and cemented into the base of a concave piece of opal. The appearance is then that of a boulder opal, dark in colour. The sighting of flecks of colour in the ironstone Boulder doublet does not guarantee anything as it is often flecks of white opal mixed with the ironstone. The overall effect is that the base appears to be natural boulder opal. A vein of colour in the base is useful as this does not occur in doublets.

Triplet Laminate

A three piece man made opal usually dark in appearance. The top surface is always either quartz or synthetic quartz, or hardened glass and the base is usually vitrolite, snowflake obsidian, opal potch, plastic, or, blackened glass. Natural Opal as a very thin slice is glued in between the top and base.