Opals
Opal is a hydrated silica gemstone valued for play-of-colour — the shifting spectral flashes that appear as light moves across the stone. Australia produces most of the world's precious opal, and black opal from Lightning Ridge is the rarest and most valuable variety. At Ministry of Gems our opals are hand-selected by our FGAA gemmologist from trusted Australian cutters and miners, graded in Sydney for body tone, brightness and pattern, and always described as solid, doublet or triplet.
We buy opal the way we mine our own sapphires: directly, and with nothing left unsaid. Every stone is examined in Sydney by our FGAA gemmologist, typed as solid, doublet or triplet, with any treatment recorded, independent laboratory certification arranged on request, and free lifetime re-authentication.
Common questions
How much does a black opal cost per carat?
Black opal is priced on body tone, brightness, pattern and size rather than carat weight alone. As a guide, commercial black opal runs roughly AUD 200 to 800 per carat, good gem quality AUD 1,000 to 5,000, and the darkest, brightest Lightning Ridge stones well beyond that. Crystal and boulder opal generally sit lower, from about AUD 50 per carat.
What is the difference between a solid opal, a doublet and a triplet?
A solid opal is one piece of natural opal, cut and polished. A doublet is a thin slice of opal glued to a dark backing to deepen the colour. A triplet adds a clear quartz or glass cap on top. Doublets and triplets are assembled, worth far less, and can separate if soaked. We state which one every stone is.
How do you care for an opal, and can you wear one every day?
Opal is about 5.5 to 6.5 on the Mohs scale, softer than sapphire, so it wants a protective setting and careful wear. Clean it with a soft cloth and lukewarm soapy water. Never use an ultrasonic or steam cleaner, and avoid sudden temperature changes. For a daily engagement ring, a bezel setting and a spare-wear habit help considerably.
Is Ethiopian opal the same as Australian opal?
No. Most Ethiopian opal is hydrophane: it absorbs water, so it can turn transparent or cloudy and lose play-of-colour until it dries out. Wetting also risks permanent damage, as staining and crazing do not reverse on drying. Australian opal is not hydrophane and is far more stable. Ethiopian material is also more often smoke-treated or dyed. We deal in Australian opal and disclose the origin of every stone.
