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OPAL INFORMATION

HISTORY:

Appearing to entrap fire and light in a myriad of colours, Opal is renowned as Australia’s national gemstone.
Between 65 and 140 million years ago (the Cretaceous Period) much of central Australia was an inland sea bearing sediments rich in silica. Over time this sea receded leaving the silica deposits and forming a region which is now mostly desert (the Great Artesian Basin). Changes to these sediments caused by heavy weathering approximately 30-40 million years ago allowed the silica to dissolve and seep into the crevices and cracks of the earth. This silica solution hardened to form what we now identify as opal. However not all opal formed has the majestic play of colour of Australia’s precious opal. All opal is unique, and the colours and patterns within each stone changing with angle and view. No two opals are exactly alike and it is their ever changing rolls and flashes of colour that make opal a truly fascinating and beautiful gem. Opal forms in three key regions around Australia- New south Wales, Queensland, and South Australia- and we provide the world with 95% of this gem.

What better gift than an Australian precious opal ………………

TYPES OF OPAL:

Black and Semi Black Opal:
Typically found in Lighting Ridge, New South Wales, a black opal is distinguishable through its dark grey or black base colour. This naturally dark backing works to enhance the brilliance of the diffracted opal colours. A black opal’s rarity and depth of colour makes it the most valuable and sought after opal: the sharper and brighter the colour of black opal, the higher its value.

Boulder Opal:
Formed on an ironstone based rock, boulder opal is found mostly in Queensland. Similar to black opal, Boulder opal possesses a darker base colour enhancing the opals brilliance. The opal occurs as a thin uneven layer naturally adhering to the ironstone, which often protrudes to the surface when cut. Depending on how boulder opal is polished it can be very smooth and glossy or quite rough, and is often cut in irregular shapes adding to its uniqueness. In terms of value, Boulder opal which has a full face of diffracted brilliant colours is often prized above ‘matrix’ opal which possesses ironstone intrusions.

Light Opal:
Light opal is found primarily in South Australia. The term light opal refers to both the crystal opal and the milky or white opals with both types being found in the same regions. Crystal opal can be distinguished by its transparency when held against a light background, and brilliance of colour when placed or ‘enhanced’ against a dark background. White opal on the other hand possesses a very light natural backing and displays a softer tone of diffracted colours in comparison to black or boulder opal. In terms of value, light opal because of its abundance is generally less expensive but no less popular or attractive.

Doublet Opals: Doublets are made by laminating a thin slice of colourful Light Opal, to a layer of dark material (either opal potch or a slice of boulder). The dark backing enhances the opals natural colours giving the effect of high quality black opal. Generally, doublets require less opal material and therefore are available at a lower cost.

Triplet opals: Triplets are made by attaching an even finer slice of opal to a dark base and then adding a crystal cap for protection. Triplets can range from souvenir quality to gem quality, with the best specimens showing the brilliant colours of fine black opal. Only a thin slice of opal material is used in the creation of triplet opal, hence the cost is generally more attractive than a doublet, or a solid black opal. Typically both varieties are water sensitive and hence stones should not be immersed. An opal is a stone you will treasure forever.

VALUING OPAL:

Opals are unique and no two stones are exactly alike; this makes opal valuation a complex process. All people appreciate natural beauty in different ways, and that is what makes buying an opal such an exciting personal experience. As members of the AOAGIA Opal Strike adheres to industry standards on grading regulations and are renowned for being very generous with our grades and prices. Below is a brief list of the factors which are used to determine the value of an opal:

Its origin: Generally black opal from New South Wales, due to its rarity is valued over boulder and light opal which tend to appear at greater quantities in the ground. Furthermore, the darker the opals base colour the more brilliant its diffracted colours, which adds to its value.
Its type: Solid opal or opal with a naturally occurring base colour possesses higher value than doublet or triplet opals which have a created backing attached to them. However, a gem grade triplet can exceed the value of a solid opal which has flat or dull colours.
Colour: An opal comprising of a spectrum of colours is priced above an opal which displays predominantly one hue. In order, red is generally considered the most valuable of colours due to its rarity and beauty, then orange, yellow, green, and blue.
Brilliance and Brightness: Independent of its body colour, an opals brilliance or brightness adds to its value. Furthermore, an opal with more vibrant or brilliant colours is valued above an opal with flat or dull tones.
Pattern: An opal with a ‘rolling’ or moving flash is prized above opals with smaller flecks or ‘pin fire’ patterns. Similarly opals with ‘harlequin’, ‘Chinese writing’, ‘ribbon’ or ‘straw’ patterns are highly sought after. (please contact us for more information on valuing opal)

CARING FOR YOUR OPAL:

Caring for solid opal is really very simple. Opal has a hardness of about 5.5 to 6.5 measured on the Mohs' scale of hardness.(Compared to this diamonds are harder at approximately 10, garnets, the same at approx. 6.5 and gold is much softer at approx. 2.5 - 3.) Therefore, opals, like any other gemstone can be broken, chipped, scratched, or lose its shine with heavy wear and tear. Solid opals can be immersed in water without a problem, however doublets and triplets will stay in their original form longer if water is avoided.

By simply treating your opal with care and respect, its original form will last indefinitely. To clean your opal, simply rub over it with a damp cloth to remove any build up of perfumes or other chemicals.