Photo: Danny Sanchez
Opal is one of the most beautiful and mysterious gemstones on earth. But how is opal formed and what is it that makes this gemstone so unique and captivating? The answer, like many mysteries of the universe, lies within.
Nature’s miracle: opal’s ‘play-of-colour’ and patterns
Opal is renowned for its brilliant, colourful spectrum and broad range of distinctive patterns, with its most famous attribute being its ‘play-of-colour’. As an opal is turned in the light and viewed from different angles, a beautiful movement of colour is seen across the face of the stone in spectacular, iridescent patterns.
These patterns have many forms and names including Harlequin, pinfire, Chinese writing, flower garden, mackerel sky, flagstone and rolling flash, among others. The brighter and more vibrant opal’s colour and patterns are, the more highly prized and valuable the gemstone is.
Weird science: how opal is formed
Opal’s intrigue also lies beneath its surface, and the science behind why it looks the way it does is interesting to know, even if you’re not an aspiring geologist!
Opal is found in rock that formed anywhere from 65 to 135 million years ago, usually located in arid inland areas of Australia which were once covered in water as part of the Great Artesian Basin.
Over millions of years, a quartz-like mineral known as silica mixed with water and seeped into cracks and cavities of the rock. As this mixture gradually dried out over time, a hardened gel containing layers of tiny silica spheres formed, creating what is known today as opal.
Colour my world: where size does count
In precious opal, the silica spheres are layered and packed in an even, regular way. As white light, for example sunlight, hits the layers of spheres and spaces in between, it breaks up into a full spectrum of wondrous colours.
The colour seen in an opal is dependant on the size of the silica spheres and the spacing between the layers. Large spheres result in a red colour – the rarest and most valuable colour of all – while medium-sized spheres commonly result in green and blue colours, and smaller spheres create violet tones.
Whatever the colour or pattern found in opal, there is no denying its magnificence and versatility as an eye-catching gemstone that looks stunning in any style setting be it an opal ring, pendant, earrings or other forms of jewellery. Opal really is THE gemstone of the decade and its popularity is set to continue far beyond the New Year.