No two opals are alike — each one flashes its own unique play of colour, like a galaxy captured in stone. But opals also come in several types and qualities, so a little knowledge helps you choose well. Here is our gemmologist's guide to buying opals.
What gives opals their colour?
An opal's magical flashes of colour — called play-of-colour — come from microscopic spheres of silica inside the stone that diffract light into spectral colours. The more vivid and varied the play-of-colour, and the more of the stone it covers, the more prized the opal.
Solid, doublet or triplet?
- Solid opal: a single, natural piece of opal. The most valuable and durable type.
- Doublet: a thin slice of natural opal bonded to a dark backing to enhance colour. More affordable than solid.
- Triplet: like a doublet, but with a clear protective cap on top. The most affordable option.
None is "fake" — they simply offer different price points, and we always disclose which type you are buying.
Body tone and brightness
Opals range from light (white or crystal) to dark (black opal). Black opals, with their dark body tone, make play-of-colour appear especially vivid and are the most prized. Brightness — how vivid the colour flashes are — is one of the biggest factors in an opal's value.
What to look for
Look for bright, varied play-of-colour across as much of the stone as possible, a pleasing pattern, and no distracting cracks. Because opal value is so nuanced, buying from an expert matters: every opal we sell is assessed in-house by our FGAA-qualified gemmologist.
Caring for your opal
Opals are a little more delicate than sapphires, so they appreciate gentle care. See our guide on caring for opals to keep yours brilliant for life.
Common questions
What makes one opal worth more than another?
Body tone comes first — darker body tones are generally rarer, which is why black opal is generally the most prized, though a brilliant light stone will outprice a dull dark one. After that come brightness, the colours present, pattern, face coverage, shape and cut, size, and the absence of cracks or sand inclusions, each taken in turn in <a href="/blogs/news/what-determines-australian-opal-value">what determines an Australian opal's value</a>. Opal is sold by the piece as often as by the carat, because face size and shape matter more than weight.
Are doublets and triplets real opal?
Yes. A doublet is a slice of natural opal bonded to a dark backing; a triplet adds a clear cap on top. Both contain genuine natural opal and neither is a fake — but they must be disclosed, they are worth less than solid opal, and they are more vulnerable to water and long immersion because of the bonded join. We always tell you which type you are buying.
Where in Australia do opals come from?
Australia has historically produced the large majority of the world's precious opal, and it has been the national gemstone since 1993. Black opal comes principally from Lightning Ridge in New South Wales. White and light opal comes principally from Coober Pedy and the South Australian fields. Boulder opal is Queensland's — it forms in seams and pockets through ironstone and is cut with that host rock left on the back.
Can I wear an opal every day?
You can, with a little thought about setting. Opal sits at about 5.5 to 6.5 on the Mohs scale, against 9 for sapphire and 7 for quartz, so everyday grit can scratch it. It has no cleavage, but it does not like knocks or sudden changes in temperature. Earrings and pendants live an easier life than rings; if you want opal on your hand daily, choose solid opal and a setting that shields the stone's edges.
Does an opal come with a certificate?
Warm soapy water and a soft cloth only. Never put an opal in an ultrasonic or steam cleaner — opal is hydrated silica, holding anywhere from a few per cent water up to around twenty per cent, and both the heat and the vibration are a real risk. On paperwork: every piece is assessed in-house by our FGAA-qualified gemmologist, and certification is available on request. Re-authentication is free for the life of the piece.
What is the most valuable type of opal?
Generally, solid black opals with bright, varied play-of-colour command the highest prices.
Sources and further reading
- Opal Description — GIA Gem Encyclopedia — Gemological Institute of America
- Opal Quality Factors — GIA — Gemological Institute of America
These are independent gemmological authorities, cited so our statements can be checked against them. Ministry of Gems® is not affiliated with these organisations. Checked August 2026.