Like its flora and fauna, opal is symbolically Australian.
Opal embodies the spirit of the tenacious and vibrant people of Australia. It truly is an ‘opal hearted
Opal – National Gemstone of Australia
For more than 100 years Australia has maintained its position as the world’s leading opal producer, responsible for as much as 95% of annual global output.
This foremost position is unlikely to be relinquished anytime soon given that Australia is home to the largest and most widespread deposits of precious opal in the world.
What differentiates precious opal from common opal or ‘potch’ is its ‘play of colour’, whereby intriguing light and colours move over the surface of the stone, this rare phenomenon is not observed in any other gemstone.
Perfect Conditions for the Formation of Opal
Hundreds of millions of years ago the newly forming Australian continent was covered by a vast inland sea which gradually receded leaving behind a huge sedimentary basin.
The basin filled with flat lying Cretaceous sands and clays that were later deeply weathered releasing soluble Silica. The Silica rich solution found voids (fossils, cracks, crevices) to infill and slowly hardened into opal over the last twenty odd million years.
Commercial opal production is
concentrated within the outline of the
Great Artesian Basin spanning four States and one fifth of the Australian landmass.
Climatic conditions were ideally suited to the slow steady growth and solidification of Precious opals. On average Australian opals are more stable and harder than most opals found elsewhere on the planet.
The marvelous fossil and mineral replacement by opal is virtually unique to Australia’s sedimentary deposits, whereas opals found outside of Australia are predominantly volcanic in origin.
Three Varieties of Natural Australian Opals
Light opal has a colourless to white body tone, varying from transparent to opaque. Generally found as horizontal or vertical seams. Coober Pedy in South Australia is historically the most prolific producer of this well-known variety.
Black Opal has a black to dark grey body tone, varying from translucent to opaque. Found mainly as small rounded nodules at Lightning Ridge in New South Wales where they are known as ‘nobbies’. Their dark base serves to highlight the changing patterns and the intensity of the colour flashes seen in the stone.
Magnificent black opals are the most expensive per carat, rivaling diamonds in price; they are arguably the rarest of all gemstones.
Boulder Opal is found exclusively in outback Queensland, it can have a light or dark body tone. The opal forms as veins or kernels embedded within ironstone boulders.
‘Yowah Nuts’ are found at Yowah, Boulders at Quilpie and ‘Pancake’ Boulders are found at Winton. These beautiful stones are cut with the natural ironstone left intact as a backing or matrix. Boulder is affordable and offers a broad selection, from scenic or ornamental stones to select gems, each piece is infinitely different.