Mesmerising opals

The October birthstone, opals are famous for their unique and intense colouring, and have appeared in ancient mythology and folklore from cultures around the world.

Opals feature in many Dreamtime stories told across Australia. One from the Yuwaalaraay people of Wallangulla (Lightening Ridge) describes the formation of opals from the scales of Gurria, the crocodile slain by the creator god Baiame. In Greek mythology, Zeus, King of the Gods, was believed to have shed tears of opal after defeating the Titans in battle.

Pliny the Elder, Roman author from the 1^st century, wrote of opals, “For in them you shall see the living fire of ruby, the glorious purple of the amethyst, the sea-green of the emerald, all glittering together in an incredible mixture of light”.

How opals are formed

Formed from microscopic spheres of silica, opals achieve their mesmerising colour through light diffraction. When a white light enters the top of the opal, the light waves bounce and refract through the spheres and the gaps in between. As the light passes through, it diffracts or splits like a prism, bouncing back to the top of the stone a dazzling array of all the colours on the spectrum.

An Australian treasure

Since the early 1900s, Australia has supplied over 95% of the world’s global output. The first commercial mine to open was in Lightning Ridge, New South Wales in 1903, the mine now famous for its black opals. Coober Pedy, South Australia was next to follow with the opening of the Mintabie mine in 1922, and the Andamooka mine in 1930. The largest percentage of opals today come from the 70 opals fields around Coober Pedy.

Opals in jewellery

The kaleidoscopic gem, opals have a rating of 6 out of 10 on the Mohs Hardness Scale. This delicate stone is best worn as necklaces and brooches but can also last for years in protective setting in rings and earrings.