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Table 1: Types of Solid Natural Opal
In addition to solid opal, a number of other varieties composite opal are widely available, as outlined in Table 2 below. Composite stone are generally more affordable than solid stones as smaller amounts of precious opal are used. In all cases, thin slices of opal are glued to a backing of black backing material. |
| Opal variety |
Example |
Identifying features and rareity |
Area of Origin |
| Light opal |
 |
White or light appearance.Most abundant and affordable |
Usually South Australian fields though some from other areas |
| Crystal opal |
 |
Transluscent appearance - a printed page would be roughly visible through the stone. Relatively abundant. |
Most opal fields |
| Boulder opal |
 |
Usually thin layer of precious opal naturally adhering to brown ironstone host rock. Relatively abundant |
Queensland opal fields |
| Andamooka Matrix Opal |
 |
Black or darkish bodied opal with bright specs of colour. This is chemically treated Limestone matrix with precious opal in voids. Not common |
Andamooka South Australia opal field |
| Dark opal |
 |
Precious opal with a grey or darkish appearance when viewed from the front. Dark opal is relatively abundant |
Usually Lightning Ridge area in NSW or Mintabie in South Australia |
| Black opal |
 |
Precious opal that has a black appearance when viewed from the front. Only opal that looks as dark as the N1-N4 body tone scale (below) can be truly called a black opal.Rarer than light or dark opal |
Usually Lightning Ridge area in NSW or more rarely Mintabie in South Australia |
Table 2: Types of Composite Opal
While most composite stones are made from natural opal, occasionally synthetic opal is used in doublets or triplets. Consumers should ask the supplier to confirm whether opal used in composite stones is natural. Also note that whilst composite stones generally have the appearance of black opal, none can be correctly described as black opal. |
| Opal variety |
Example |
Distinguishing features |
Area of Origin |
| Doublet |
 |
Thin slice of precious crystal opal glued to black backing material . When the backing is brown ironstone it is often called a boulder doublet |
Any opal field producing crystal opal |
| Triplet |
 |
Thin slice of precious crystal opal glued between crystal cap on top and black backing |
Any opal field producing crystal opal |
| Mosiac |
 |
Thin chips of precious crystal opal glued onto black backing, can be used in doublets, triplets or on watch faces. |
Any opal field producing crystal opal |
| Inlay |
 |
Small thin pieces of precious crystal opal glued directly into channels in jewellery |
Any opal field producing crystal opal |
How to care for your Opals
Opal jewellery requires no greater care than other jewellery mounted with stones such as diamond, ruby emerald, tanzanite or turquoise.
You should never wear any jewellery in rough conditions such as to the beach or during activities where it may get knocked by metal or hard objects (eg washing up).
In these conditions, stones get dislodged from their settings, gold gets scratched and stones get chipped (even diamonds) and opal should be treated the same as all other stones - with respect.
Opal requires no special treatment or care. As with other stones, grime from wear can be wiped off with a damp tissue or cloth. |
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