Who can look into an opal without seeing the rainbow? The Opal is a semi-precious stone which combines all colours at once and could be divided into different categories.
But the best-known categories are the dark or black Opal (the most valuable one) and the white or the light Opal. These opals are opaque with an endless play of colour, fire, also named opalising.
Another special but not so well-known Opal, the transparent Fire Opal, has an intense and typical reddish-orange colour but looks very different from the other Opals. But what causes this effect? Only in the 1960s, when Australian scientists analysed the opal with an electron microscope, they discovered that small spheres from silica gel caused interference and refraction. The light that returns to the eye, after being reflected from the surface to these small spheres, is subjected to interference and is broken up into a fantastic play of rainbow colours. They all show in their own special way the unique play of colours.
Before the 19th century, Opals were relatively rare. The first opals originated from Hungary were already known by the Romans. The original name of opal was probably derived from Sanskrit “upala”, meaning valuable stone. This was probably the root for the Greek term ‘opallios’, which means colour change. In the days of Roman antiquity there existed a so-called “opalus”, or a stone from several elements.
Pliny the Elder, the famous natural philosopher, called the Opal a gem which combines the best possible characteristics of the most beautiful of gemstones: “The fine sparkle of Almandine, the shining purple of Amethyst, the golden yellow of Topaz, and the deep blue of Sapphire so that all colours shine and sparkle together in a beautiful combination “.
Funnily the first Opals from Hungary were called Oriental Opals because they were carried to the Orient and then shipped to Europe. Other mines in Mexico and Honduras were already known, but the opals were less abundant.
In 1849 the first Opal block was accidentally found by a kangaroo hunter in Australia. Only in 1890, the first prospection started at White Cliff mining. But the history of Australian Opal began millions of years ago when parts of Australia were covered by a vast inland sea, and stone sediment was deposited along its shoreline. When the water masses flooded back, they flushed water containing silica into the resulting cavities and niches in the sedimentary rocks, and also the remains of plants and animals were deposited there. Slowly the silica stone transformed into Opal.
So, from the 19th century, Opals appeared more frequently. During the Art Nouveau period (end of 19th century) jewellery artists even preferred to use opals because of their subdued charm and different aspect. Later during the Art Deco period, the Opal was still a popular gemstone and was often surrounded by enamel or diamonds.
While Australia is now the biggest supplier of fine Opals, other mining countries, as Brazil, USA, Indonesia, Ethiopia and Mali offer very nice items too. It is a real pity that these “fire gems” are not more often seen in contemporary jewellery.
Text ©World Luxury Jewellers.
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