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Black Opal
"Of all precious stones, it is Opal that presents the greatest difficulties of description, it displaying at once the piercing fire of Ruby, the purple brilliancy of Amethyst, and the sea-green of Emerald, the whole blended together and refulgent with a brightness that is quite incredible".
Pliny the Elder (23-79 AD), Historia Naturalis
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An Opal mine in 1886, located at White Cliffs in the Australian State of New South Wales. Only discovered in Australia in 1849, today around 95 percent of the world's Opal hails from this sunburnt country |
In my mind, Pliny the Elder was the leading authority on gemstones in the classical world, and the reason he's quoted a lot in this book, is that 2,000 years on, many of his observations still ring true. Back in Pliny's day, Opal pretty much came from one place in the world, Czernowitza in modern-day Slovakia (formerly part of Hungary, thus the old term 'Hungarian Opals'). Rome never did manage to make it part of their Empire, so it retained an exotic appeal and genuine rarity, which along with its unique physical beauty, assured its popularity. But before Rome there was Greece, and while Herodotus, Plato and Theophrastus gave Opal a plug, around 500 BC, Onomacritus, compiler and forger of oracles (yep, he got busted) said, "The delicate colors and tenderness of the Opal remind one of a loving and beautiful child". This comparison probably isn't originally his; ancient Greeks and Romans often compared Opal's beauty to that of a favourite child. While both cultures cherished Opals, the Greeks believed it possessed the power of foresight, invisibility and prophecy, while the Romans considered them symbols of hope, love and purity. The Romans even wore them as talismans for protection from danger, which is definitely apt for a gemstone with a rainbow trapped within.
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Prized for its flaming rich colours, Boulder Opal's popularity has skyrocketed over the last 20 years. Created when Opal fills cracks and crevices in ironstone boulders, Boulder Opal occurs sparsely over a huge area of Queensland centred on the town of Quilpie, but extending to Winton in the north and Cunamulla in the south. While Boulder Opal with visible ironstone is called 'opal with matrix' and Boulder Opal with no ironstone visible is called 'opal in matrix', most Boulder Opal includes the host brown ironstone cut to the contours of the Opal vein. This typically results in Boulder Opals with striking, irregular free-form shapes, making each one unique |
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Moving ahead in history, Shakespeare used Opal a lot in his plays to portray lavish magnificence, calling it, "this miracle queen of gems" in 'Twelfth Night'. Queen Victoria, much like Cleopatra's second Roman boyfriend Marc Anthony, was a ruler big on Opal. In fact, she actively dispelled myths of Opal being unlucky as a result of people missing Sir Walter Scott's use of metaphor in 'Anne of Geierstein' (1829).
If Pliny liked European Opal, he would have gone wild for the Australian Black, the 'king of opals'. While I try not to play favourites, Black Opal is definitely special to me. After all, since 27th July 1993, Opal has been Australia's national gemstone. This is not surprising, considering 95 percent of Opal hails from my homeland, but I guess we should also remember that Australia's Opal fields are bigger than those found in the rest of the world combined. With only 25 percent of Opal mined gem quality, understanding this October birthstone is easier than you think.
Our modern word for this gem has an interesting entomology. Opal is derived from the Roman 'opalus', which in turn is from the Greek 'opallios', meaning 'to see a change'. While another possible Greek origin is 'opthalmios' (eyestone), the original source of the name is probably the Sanskrit 'upala' (precious stone), lending credence to India once being a source of Opal for ancient Rome. To understand how Australian Opals were formed, we have to travel back in time 140 million years. Dreamtime legends passed down by storytellers have been part of indigenous Australian culture for over 60,000 years. For tribes from the Andamooka region in South Australia, the Opal was known as the 'fire of the desert' and was linked to creation myths. Their ancestral creator came down to earth on a great rainbow, which turned the rocks it touched into resplendent Opals, coloured with the hues of a rainbow.
In reality, we need to look to a huge inland sea and a resulting geological feature called the 'Great Australian Basin'. The majority of Australia's Opal fields are located in the basin and were formed from the weathering of sandstone deposited over older host rock. The structure of Opals is unique and comprised of tiny spheres of silicon dioxide forming a pyramid-shaped grid, interspersed with water. It's the refraction of light through the spaces between these spheres that produces Opal's characteristic and unique 'play of colour' - the flashes of colour that change with the angle of observation. Interestingly, Opal without 'play of colour' has its silicon dioxide spheres more randomly arranged. Apart from their colourful brilliance, Australian Opals are also valued for their stability, a key consideration for a gem containing around six percent water.
Now famous across the world for its brilliant colours, Australian Opal was discovered in 1849 and by the end of the 19th century started to dominate the world's supply. But this wasn't without some initial resistance. Perhaps a little recalcitrant, the Hungarians claimed Aussie Opal wasn't the 'real deal', despite the fact that by the 20th century, their own deposits were pretty much exhausted. Today, most Opal is sourced from a handful of Australian mining areas, including Andamooka (1930), Coober Pedy (1915), Lightning Ridge (1902), Mintabie (1931), White Cliffs (1890) and the Queensland Boulder Opal fields (a vast area discovered in 1869 centring around the town of Quilpie). Before we cover how to judge a Black Opal, it's important to know how different Opals are classified.
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Jelly Opal, also known as Crystal Opal, is transparent to translucent and because of the absence of potch, either doesn't have a body colour or if present is described as White Crystal Opal, Dark Crystal Opal or Black Crystal Opal. While Jelly Opal is found in all Australian gem deposits to some degree, this specimen hails from Andamooka in South Australia
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While there are several classification systems, they all relate to the host rock (also known as 'potch' or 'matrix') on which Opal forms and their resulting transparency and body colour (the base colour on which Opal's 'play of colour' is visible). Black Opal has a black body colour and may be opaque with some translucency, particularly when held to a strong light source. While the main classifications are included under photographs in this section, Grey Opal is a term seldom used, with its specimens typically being grouped in the 'black', 'dark' or 'semi-black' categories, but it is translucent to opaque with a grey body colour. Opaque Opal with ironstone (boulder) potch included in the cut is called Boulder Opal. Take note that not all Opal has 'play of colour'. Fire Opal is transparent to translucent crystal Opal with virtually no 'play of colour', displaying oranges, reds, yellows and, since a recently discovered Brazilian deposit, also blues. Peruvian Opal is a rare variety that exhibits exquisite translucent blues, pinks and greens, also without 'play of colour'. Another variety with no 'play of colour' is the translucent yellow and green Opal from Tanzania.
As each Opal displaying 'play of colour' has its own personality, individual preferences play a big part. Despite this, Black Opal is the most valuable variety, simply because of the contrast and intensity afforded by its black body colour. One way to understand this is to imagine painting a row of windows black (Black Opal), grey (Semi Black Opal), white (White Opal) and colourless (Jelly Opal), then randomly spray painting each window in all the individual colours of the spectrum: blue, green, orange, red, violet, and yellow. Obviously, the window painted black is going to make the colours appear more intense. This is key to appreciating Opal, because when 'play of colour' is present, its value lies in the brilliance, brightness and strength of colours displayed.
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Matrix Opal, also called 'opal with matrix', is any Opal where the host rock is visible face up. This specimen is from Central Queensland and shows a black host rock (matrix) embedded with brilliantly colourful flashes of Opal |
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Superficially, assessing Opals appears incredibly simple, but when an expert starts dissecting the combinations of colours and patterns possible, much like Jade, you're heading into complex territory. But thankfully, there are some easy to understand paradigms that not only apply to Black Opal, but any Opal displaying 'play of colour'. Just be aware that for darker coloured Opal (black and semi-black) opacity demands a premium and in lighter Opals (white and jelly) transparency demands a premium. In the marketplace, there is a definite hierarchy of colours, with red being the most valuable, followed by orange, yellow, violet, green, and then blue.
Opals whose 'play of colour' flashes in the rare reds are generally more valuable than those with just blue and green, but as with all gemstones, colour preferences are subjective.
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Semi Black Opal (also known as Dark Opal) is translucent to semi-translucent and has a body colour in-between grey and black. As Black Opal is generally more opaque, opacity is the criterion that divides black and semi-black Opal. This example is from Mintabie in South Australia |
An Opal with a 'play of colour' comprising more than half of one colour is named for its primary hue, while an Opal with three or more hues is called 'multicolour'. Even though the presence of red increases a Black Opal's rarity and value, it's typically valued lower than a multicolour that shows several colours. The patterns of colour also affect value, with large patches of colour priced higher than those with small patches of colour. Professionals often communicate these patterns using colourful self-explanatory names such as Chinese writing, harlequin, peacock and pin-fire. While 'play of colour' and strong opalescence (the silver to bluish-white light that shimmers and glides over an Opal's surface) rarely exist together, Opal with an opalescence that reduces the brilliance and intensity of its colour play will be priced accordingly. The biggest thing to remember is that due to its layered colours, Opal is one of the most 'artistic' of all gemstones. So when making your selection, try remembering the old saying, "I don't know much about art, but I know what I like".
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White Opal, also known as Light Opal, is the darling of everyday fashion jewellery. It is translucent to opaque with a white body colour. Coober Pedy in South Australia is the main source for this variety. Named for its Opal miners, 'Coober Pedy' means 'white man's hole in the ground' and is a corruption of a local indigenous Australian phrase, 'kupa-piti' (boys' waterhole) |
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Once you've settled on a colour play you find appealing, you must consider the cut. Thankfully, assessing cabochons is straightforward, just look at their finish, shape and proportion. While symmetrical ovals will demand a premium, Opal that is cut too thin or thick, whose dome is too shallow, or has a finish that is cracked or crazed, will be priced accordingly. Due to their rarity, slithers of Black Opal are sometimes joined with other material to create doublets (Opal plus a backing material) or triplets (Opal with a top as well as a back). These are understandably more affordable, but do be aware that these are manmade composites that should be sold as such. Although Opal is relatively durable, it does have some special care requirements (click here for more). While Black Opal is primarily sourced from deposits at Lightning Ridge in New South Wales, production at Lightning Ridge is half of what it was 10 years ago. Unfortunately, this is somewhat echoed at all of Australia's major Opal deposits, markedly increasing scarcity. Apart from Australia, other Opal sources include Brazil, Ethiopia, Mexico, Peru, Tanzania and the U.S.A.
As colourful as its country of origin, Black Opal is definitely a gemstone with its own unique personality and character. Like Australia itself, Black Opal is easy to appreciate; it's easy to become enchanted by its unrivalled beauty. In the words of the famous Australian poet Dorothea MacKellar: "An Opal hearted country a wilful lavish land, all those who have not loved her you will not understand".
Blue Fire Opal
Newness, rarity and beauty are what make Blue Fire Opal special. The debut of Blue Fire Opal has been shifting perceptions in play since the time of the Aztecs; namely, Fire Opal is red, orange or yellow. Blue Fire Opal is transparent to semi-translucent, with a colour similarity to pastel Tanzanite, pretty icy cool violet-blues to steel blues. It also has occasional opalescence, the milky blue appearance of Opal caused by the reflection of light, which combos nicely with its body colour. The first significant production of Blue Fire Opal occurred in December 2007, when it was discovered by sheer chance at the Boca Rica mine in Brazil's Piaui State (pronounced: Pee-Ow-Ee). The Piaui State has garnered praise aplenty for its Opals, being compared to those from Australia. With less than one-tenth of a percent of the rough mined useable, the monthly output of Blue Fire Opal is sporadic.
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Fire Opal
Fire Opal, also known as Mexican Opal, Mexican Fire Opal, Cherry Fire Opal or Sun Opal, is aptly named for its transparent to semi-translucent fiery reds, oranges and yellows. Treasured in the Americas since the time of the Aztecs, Fire Opals were once called 'quetzalitzlipyollitli' and while I can't pronounce this word, it means 'gemstone of the bird of paradise'. Fire Opal is mainly found in Mexico, but it has also been unearthed in Brazil, Ethiopia, Mali, Tanzania, and occasionally Australia.
| Thanks to Australian movies, television and tourism advertising, you're probably already aware of some classic Australian slang like 'G'Day Mate', but unless you've visited an Opal field, terms like 'floaters', 'noodling' and 'ratters' will probably fall on deaf ears. Well, I'm here to help! Floaters are Opal that is visible from the surface and typically indicative of an underground deposit, noodling is hunting through old mine tailings to find Opal that others missed and ratters are people who poach Opal from another's claim - a big no, no that was once arbitrarily and severely punished! |
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