What is precious opal?
Of all the gemstones in the world, precious opal is perhaps the most beautiful. But what do we mean by precious opal?
Opal can be divided into two varieties: precious and common/potch. Precious opals are the gemstones with the irregular, iridescent colour patches (called play of colour) over either a pale background (white opal) or a dark background (black opal).
Black opals are particularly sought after and valuable, and especially those with reds and yellows in their iridescent colour spectrum. Despite the name, black opals tend to have a dark blue base colour.
How are opals formed?
Opal is formed in the cavities and fissures of rocks, when low-temperature water invades those gaps and evaporates, leaving behind many spheres of silica.
The silica spheres, packed together, interfere with the light as it tries to pass through them, separating what we normally perceive as white light into its constituent colours (blue, green, yellow and red).
The result is the precious opal gemstone with shifting colours, often woven into background rock. It's a gemstone that has fascinated humans from the day it was first found, with fine antique opal jewellery at auction today often reaching exceptionally values.
Opal and Aboriginal legend
Australian Aboriginal legend says that opals appeared when the Creator first descended to the Earth with a message of peace, travelling down the arc of a the rainbow. When his foot touched the ground, the rock that covered the Earth began to sparkle just like the rainbow he traveled on.
Aboriginals prized the colourful stones, as the did the ancient Greeks who thought opal bestowed the powers of foresight and prophecy, while the Romans considered precious opal a symbol of purity and hope.
Opal as October birthstone
Aside from it's very obvious beauty, today we prize opal as one of the birthstones for October and opal stones are very popular set in rings, pendants and earrings.
Sometimes the stones you see will be entire precious opals fashioned as a cabochon (smooth dome), sometimes they will be opal doublets (slices of precious opal cemented to an ironstone base) and sometimes they will be opal triplets (a slice of precious opal cemented between a transparent top and a dark base).
There are huge cost savings when it comes to doublets and triplets, with very little loss the beauty of the stone.
Caring for Opal Jewellery
Opal is a soft gemstone and great care needs to be taken when wearing it, especially in rings on the hands. Knocks and bangs need to be avoided, so take the ring off for any activity where it could take a hit and never put it in an ultrasonic jewellery cleaner.
Keep the stone out of hot sunlight and away from heat generally, including the jewellers torch - do not try and resize your opal ring!
Opal is a porous stone, so keep it away from all chemicals including perfumes, moisturisers and swimming pools. Do not store in too dry a condition, good advice is store next to moist cotton wool balls to stop the stone drying out and cracking.
History of Opal Jewellery
Opal has had an interesting jewellery history, and has been considered both lucky and unlucky at different times!
Most opals found in antique pieces were mined in Hungary, the Czech Republic or Slovakia, or were early stones to come out of Queensland, Australia. Many opal discoveries were made in Queensland in the 1870s, with the first record of Australian opal being set into fine jewellery at the Melbourne International Exhibition in 1880.
Not surprisingly, opals became very sought after in jewellery in the late Victorian and Edwardian eras, and can be found in antique pendants, necklaces, bangles and brooches in addition to the already discussed rings.
Opals could be set as a set stone and surrounded by diamonds, or they may be set with emeralds and rubies, or used as standalone gemstones in fine gold and platinum pieces.
Boulder opal antique pieces can also be found, and in boulder opal jewellery the opal is still attached to the host rock in which it formed. When these stones were fashioned, it was considered prudent for the stone's integrity to keep some of the backing rock attached.
Boulder opal pieces are hugely desirable and we have had some wonderful examples pass through our hands over the years, notably large drop pendants.
Buying Opal Jewellery Online
We stock some beautiful opal pieces, and a particular favourite is our opal and diamond engagement ring in 9ct gold.
You can view our full collection of opal jewellery here.