Ninety five percent of the world's opals are mined in Australia, mainly in Anda mooka, Coober Pedy, Lightning Ridge, Mintabie and other areas in NSW, SA and QLD.
- Black : Black opals have a rare body tone that often features an impressive play of colour.
- White: More common white or milky opals , do not reflect colour as well and are often less valuable than black opals.
- Boulder or matrix: Boulder opals , also called matrix opals, are a type of natural opal. They are mined in brown ironstone deposits. The opal is cut with the ironstone remaining in the back creating a unique and fashionable look.
- Crystal: . They have a transparent to semi transparent state that tends to reflect a fair amount of colour. Crystal opals rank under the black opal in terms of rarity and value.
- Fire: Rare red-orange fire opals are popular for their eye-catching colour.
- Doublets: Doublets are a form of composite natural opal. The stone is actually made of two pieces, a solid piece of opal cemented to a black backing.
- Triplets: Triplet opals are made out of three pieces - a solid piece of opal, the black backing and a crystal cap cemented on the top.
- Synthetic and imitation: Synthetic opals are made of materials which have the same composition and physical structure but are man-made. Imitation opals simply just imitate the play-of-colour without having the physical or chemical structure as natural opals. Synthetic and imitation opals usually appear glassier than natural opals and have a precise and organised colour scheme, typically in a snakeskin pattern.
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