Opals are found all around the globe; however, Australia produces around 95% of the world’s supply of opal. Australian opal is highly prized and this rainbow-coloured beauty is our official national gemstone.
How did opals come into existence?
The creation of this true-blue Aussie legend began millions of years ago when Australia became a new continent covered by a large inland sea and a natural sedimentary basin. When the vast sea subsided, soluble silica seeped into the cracks, crevices and fissures, gradually compressing over a period of 20 million years to create our opal.
Fun fact about opal #1: Opal is also considered a fossil. Buried in the Australian opal fields are fossils of dinosaurs and other prehistoric creatures that lived in Early Cretaceous times.
Why does opal change colour?
The magic of these rainbow-coloured gems is actually simple science. The silica spheres that sit compacted together in the crystal structure of opal are where you find the ‘play of colour’. As light hits these and diffracts, the light is split into a rainbow of colours. You will notice the colours change as you move the opal piece as light bounces around these minuscule spheres and back up to the top of the stone for a spectacular show.
Across our sun-burnt country: Where are opals found in Australia?
White Opals in South Australia
Australia’s primary source of white opal is mined in central South Australia in the dust bowl of Coober Pedy. It was given this name in 1920, derived from the Aboriginal words “Kupa Piti”, meaning boy’s waterhole
Rare black opals in New South Wales:
The beautiful Black Opal is the rarest form of opal and, therefore, the most expensive on earth. Found in the mining town of Lightning Ridge northwest of NSW in the mining town of Lightning Ridge, they display dark galaxies of colours with beautiful constellations of patterns.
Their play-of-colour or ‘fire’ can flare with blues and blue-greens through to oranges and reds.
Unique boulder opals of Queensland:
Boulder opals, an opal naturally attached to a host rock, are unique to Queensland and are only found in the mining belt stretching from Winton in the north down to Quilpie in the southwest. If fortune favours you, maybe you will even find a famous “Yowah Nut” on your fossicking travels. These ironstone-covered spherical-shaped precious opals are tinged a rusty surface colour from the ironstone outer layers and a hidden precious opal centre – hence the ‘nut’ nickname!
Fun fact about opal #2: The largest and heaviest opal in the world award goes to Australia, in particular the Andamooka mines. Known as the “Andamooka Desert Flame,” this giant weighs in at an incredible 6,843 kilograms. A home-grown hero!
Myths about our opal gemstone
Australian opals are also winning when it comes to myth-busting.
- Myth: Common myths about opals include keeping opals away from light, occasionally soaking in water to prevent them from cracking, or opals are unstable.
- Fact: Australian opal is non-porous, and during the formation of the stone, the silicon and water molecules are safely compacted and, therefore, highly stable. An opal is indeed more fragile in hardness than other gemstones, but it has a similar hardness to glass, so it’s really not as delicate as it may seem.
Opal buying tip: Buyers, be aware, as you can find doublet or triplet opals in the market. These are slices of opal between a clear top and black base, and over time water can penetrate these glued layers to become cloudy or foggy grey in appearance.
Have you got an opal jewellery piece in your jewellery box and want to know what it is? Click below to ask any questions:
Commonly asked questions about Opal
Q1. Opal is a birthstone for which month?
October babies are blessed with the opal as their birthstone. Perfect if you can’t decide your favourite colour – you get a rainbow stone!
Q2. Which opal is worth the most?
The moody black opals are a dark horse in this race. Their nightshades are the rarest opals found across the globe and, therefore, the most prized.
Q3. Can opal rings be worn by anyone?
Yes! Opal is popular with young and old and can be worn by men and women in a range of different ring styles. Be careful with our fossil friend, though, as rings can get dinged around in daily life, so it is best to take them off doing chores, manual work, gardening and showering.
Q5. What is opal gemstone good for?
With their high water content, no wonder they are rumoured for their healing properties – they are well hydrated! And who wouldn’t get creative when they gaze at the magic colours of a natural opal? Practically, opals are good for earrings and pendants, as they are more protected from wear and tear.
Q6. Is opal expensive or affordable?
An opal is as affordable as a few dollars for common potch opal with minimal play of colour, through to the rarest matrix black opal with dazzling fire on the other end of the expensive scale. A nice piece of opal with good play of colour will set you back a few hundred dollars, which won’t break the bank when designing your piece of Australian pride.