Opal, October's birthstone, is the bearer of good fortune. When the universe was completed, God scraped together all the colours on his palette and created a gemstone of mystical, flashing hues. The Romans revered Opal as a symbol of hope, fidelity, purity, and good fortune and held it to be second only to the prized emerald.
Opal is a non-crystalline gem that is formed in the ground when silica is liquefied and washed into fissures in the surrounding rock where it solidifies into a hardened gel. Tiny silica spheres create a pattern in Opal that causes a prism-like effect that produces flashes of colour.
Natural Opal occurs in several types: White Opal, the most common on the market, has a transparent or white body colour with vibrant pastel flashes of rainbow colour. Black Opal has a blue, gray or black body colour that reveals a more dramatic play of colour. Boulder Opal is most often black Opal with some of the ironstone matrix in which it occurred still intact. Crystal or water Opal is transparent, colourless opal that contains brilliant flashes of colour swimming within it. Fire Opal is transparent or translucent with a yellow to orange to red body colour that may have a play of colour or not.
On the Mohs scale of hardness, opal ranks 5-6.5. This rather porous gem is brittle and fragile. Thought should be given when designing jewellery that protects the stone from harsh wear.
Today, 95% of the world's Opal is mined in Australia, known for producing the most spectacular material on the planet. White Opal is also being produced in Brazil. Fire and crystal opal is found in Mexico and the United States (Nevada).
Use a soft dry or damp cloth to clean your Opal. In fact, rub the gem periodically with cloth moistened with olive oil to help preserve it. Do not soak your Opal in chemicals or use mechanical cleaners. Avoid heat and dry conditions that could dehydrate and crack your opal. Treat it with care to prevent sharp blows and scratches. Avoid impacts.