Precious opal is hardened silica gel, made of microscopic spheres stacked in orderly rows. When light passes between those spheres it splits into pure spectral colour, creating opal's famous play-of-colour: flashes of red, green, blue and gold that shift as the stone moves. No two opals are ever alike. Australia produces the majority of the world's supply, from the white opal of Coober Pedy to the black opal of Lightning Ridge, with Ethiopia now a major source of bright hydrophane material. Opal is the birthstone for October, and it typically holds several percent water within its structure.
Opal needs gentle handling. It is 5 to 6.5 on the Mohs scale, sensitive to sharp knocks, and sudden heat or very dry conditions can cause fine cracks called crazing. Wear it in pendants and earrings freely, and choose protective settings for rings. Never use ultrasonic or steam cleaners; a soft, damp cloth is perfect. Be aware that doublets and triplets, thin opal slices glued to backings, are common and legitimate when disclosed, but they should cost far less than solid stones. Everything we sell is clearly described and genuine.
Boulder and common opal are its close vareities, while ammolite and labradorite share its shimmering rainbow colour.
