By Maddy Robinson & Sandra Pimlott FGAA Dip D.T. NCJV Reg Valuer October 31 2019
Opals are one of the most brilliant gemstones, with varying colours and patterns formed by different methods many millions of years ago. A form of hydrated silica, an opal’s colour can range due to the size of the silica spheres, with the larger spheres giving the flashes of red and orange and the smaller giving the colour ranges in the blue green.
Some of the oldest opals in existence are from the Ordovician period, up to 595 million years old. They can be found all around the world in places such as Mexico, Ethopia, North Brazil, Peru, The United States (in Nevada and Idaho), Honduras, Indonesia, Somaliland, Slovakia and of course, Australia. Some of the oldest pieces of jewellery with opals are from Hungary and Brazil as the Australian opal fields were at that time largely undiscovered.
In Australia, opals were first discovered in Queensland in 1872, with the first Australian mines opened in White Cliffs, NSW in 1884. There are many native folklore legends surrounding opal, including the in Dreamtime legend, where the creator came down to earth on a rainbow serpent and wherever he stepped on the Earth, the ground began to sparkle and came alive with the colours of the rainbow.
The Olympic Australis remains to be the largest and most valuable opal to date, found in 1961 in Cooper Pedy, SA.
Being sedimentary, metamorphic or volcanic in origin, there are many types of opal, including:
Understand what opal you are buying. Here are some tips:
Do your research to ensure you are buying the right stone for you. Some sources sell opals that are advertised incorrectly and end up
Home care cleaning projects can hurt your opal, so taking your opal jewellery to a jeweller once a year ensures your stone stays clean and safe. Submerging the wrong kinds of opal, such as doublets or triplets, in water can permanently damage them as water can slip between the layers and degrade the stone. And obviously, do not put your opals in an ultrasonic.
Opals are a soft stone and require care. The best type of ring setting for an opal is an enclosed setting, such as a bezel setting, in order to protect the stone. Claw settings are not recommended.
When choosing an opal, start by outlining your budget. Chat to a jewellery consultant about what colours you’d like to see in your opal. High quality opals will show more play of colour throughout the stone and have more light dispersion. Opals such as harlequin opals, which show a significant amount of red, are considered the most rare.