Opal is the classic October birthstone which has now been joined by Tourmaline – the subject of my next blog. The name Opal is thought to be derived from the Sanskrit word Upala meaning “precious stone.” Most Opals are valued for their shifting colours in iridescent hues – a phenomenon known as “play-of-colour.” This attribute has inspired writers to compare Opal to fireworks, galaxies and volcanoes. Bedouins believed that Opal held lightning and fell from the sky during thunderstorms. Ancient Greeks thought Opals bestowed the gift of prophesy and protection from disease. Europeans associated Opal with purity, hope and truth. Historically, Opal was credited with possessing the virtues and powers of all coloured stones combined.
In addition to being an October Birthstone, Opal is also the stone given to celebrate the 14th wedding anniversary. Opal is mined across the globe with the richest deposits being in Australia. Lightning Ridge in NSW is famed for production of Black Opal. Boulder Opal is uniquely found in Western Queensland.
Opal is a soft stone measuring 5 to 6.5 on Mohs scale so it is prone to damage. It may be treated by impregnation with oil, wax or plastic. Opal doublets or triplets are fine slices of opal glued to a base material and covered with a thin dome of clear quartz. The safest way to clean this October birthstone is with warm, soapy water avoiding damage to the opal or filler material. Prolonged exposure to water may weaken the adhesive in Opal doublets and triplets – special care should be taken to avoid daily immersion of rings in water. Natural Opal can fracture if exposed to high heat or sudden temperature changes – so these gems need careful handling.
The image is the “Virgin Rainbow” – said to be the finest crystal Opal ever unearthed and found at Coober Pedy, South Australia.