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Black and Semi Black Opal Black Opal is solid opal distinguished by the black or very dark body colour of the stone and is highly sought after because of its beauty and rarity. Semi Black opal has a background which ranges from smoky grey to nearly black. The dark backgound accentuates the play of colour in the opal and the brighter and sharper the colours, the more valuable the opal. Most Black Opal comes from Lightning Ridge in New South Wales or Mintabie with a very small amount coming from the fields around Coober Pedy. |
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White Opal White or light opal is solid opal distinguished by a white or light background which is opaque. The play of colour is generally more subdued than black opal however, quality white opal can be brilliant and display many colours. White Opal generally comes from Coober Pedy and Mintabie in South Australia. |
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Crystal Opal Transparent or translucent opal is defined as crystal and here the colors are sharp and visible below the surface. Crystal opals come in all color variations and display bright colors. Crystal opals can be either light or dark and are solid. Crystal opal is clear enough to see through against a light surface but when viewed on a dark surface the colours really spring to life. In terms of value, the more transparent the stone is, the more it is worth. |
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Fire Opal The term "fire opal" is commonly used to describe the clear orange crystal opals which come from Mexico, some of which have a play of colour. Many have just an orange or reddish base with no play of colour and most of these stones are faceted. The term "fire" is also used to describe the dominant colour reflected or diffracted out of any opal. |
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Yowah Nuts Mined at Yowah in western Queensland Yowah nuts are opal deposits which have formed inside a nut like kernal of ironstone. They are usually very hard and can be polished to a very high gloss and are often made into attractive jewelry. |
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Matrix Opal Andamooka matrix is a very porous opal which when mined is light in colour. It is cut and polished then carbonised by treating it with sugar and sulphuric acid. The end result is a stone which looks very much like good black opal. It has a characteristic salt and pepper look and can be easily identified when looked at under a magnifying glass. Matrix opal can also be naturally formed in ironstone and this form is known as boulder matrix
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Boulder Opal Boulder opal is a naturally formed solid opal which consists of a fine layer of opal that has been deposited by nature on and in the fissures of ironstone base rock. Because it geneally has a black or very dark background colour it has the appearance of black opal. There are often inclusions in the opal layer and because the layer follows the contours of natural ironstone the shape is often very undulated. Depending on how the stone is polished it can either be very smooth or be "pockmarked" where ironstone protrudes to the surface. The irregular shape of boulder opal makes it a designers delight and most pieces of jewelry using boulder opal are very unusual. Boulder opal is found at a number of locations in Queensland with some small quantities coming from Andamooka in South Australia. |
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Doublets and Triplets Doublet Opals consist of a layer or slice of natural opal which has been bonded to a dark or black backing. The backing can be potch, black glass or ironstone boulder. These days most doublets are bonded to an ironstone backing thus forming a "boulder doublet". The dark backing enhances the colours and has the effect of simulating high quality black opal. However because less opal material is required doublets are much cheaper. Triplet Opals are similar and consist of a thin slice of natural opal bonded to a black backing together with a glass or crystal dome on top which protects the opal. Triplets range from souvenir quality to gem quality with the best specimens showing the brilliant colours of fine black opal. However because only a thin slice of opal is used the cost is much lower. Doublets and triplets may be manufactured but do contain natural opal - they are not synthetic opals which do not have the same chemical composition as natural opal. |
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Valuing
Opal Size Colour |
Clarity
and Brilliance A clear opal with rich vibrant colours will be highly valued. An opal with inclusions or opaque patches will not be as valuable as a clear stone. Pattern Your
Preference |
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Opal is a unique and beautiful gemstone which will last indefinitely if properly cared for. Generally speaking you should treat your precious opal with the same care and respect as you would with any fine jewellery. While there are some special requirements, caring for opal is really very simple providing that you keep in mind two basic facts about opal. Firstly, most precious opal contains about 6 - 10% water. Therefore opal can craze or crack when subjected to harsh, dry conditions which "dry out " the stone. Secondly, 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 about 10, garnets about 6.5 and gold is much softer at about 2.5 - 3. Therefore, opal like any other gemstone can be broken, chipped, scratched, or lose its shine with heavy wear and tear. FAQ
Can I put opals in water? Yes, solid opal can be wet or soaked in water without any problem. This is not advised if the stone is a doublet or triplet as the water may affect the cement or adhesive bonding the opal layer to the crystal cap or backing layer. How do I clean opal? Solid opal can be cleaned with a soft detergent in warm water using a soft cloth or brush. Once cleaned the opal should be rinsed in clean water to remove any residue. Doublets and triplets can be wiped with a damp soft cloth but should not be soaked. What about oils? It is not recommended to store opal in oil or glycerin - though oil will generally not soak into the stone. Oily face and hand creams should not cause a problem except that they may build up in or on the jewellery and look unsightly. This is easily cleaned off with a soft brush and warm water.
Prolonged exposure to harsh detergents and other chemicals can damage or "dry out" the stone. Be particularly careful about exposing opals and sterling silver to chlorine or chlorine bleach which will affect it. Sand and soil are abrasive and ultimately will scratch the surface of the finely polished stone and any gold or silver with it. An accidental hit or knock could crack the stone or damage the metal claws holding it into the setting. Treat all jewellery with respect and take it off before engaging in any of these activities. What do I do if my stone loses its shine or becomes scratched? You should take your opal to a reputable jeweler who knows about opal. If the stone needs re-polishing this can generally be done for a very reasonable price. He can also check for claw damage and make sure that the setting is still sound. What about doublets and triplets? Both are layered opals which do need a little more care than a solid stone. Doublets consist of a slice of precious opal which has been cemented to base of common opal potch or more commonly ironstone. Triplets are similar except that they also have a clear crystal cap cemented to the top of the precious opal slice in order to protect and enhance it. While both can be cleaned with lukewarm water and mild detergent it is not a good idea to wash or immerse them in water as this may affect the cement bonding them together. For the same reason it is not recommended to use an ultrasonic cleaner for cleaning jewellery containing doublets or triplets. How do I store my opals? Generally storing your opals wrapped in a soft cloth is all that you will ever need to do. If you keep you opals in a de-humidified atmosphere such as a safety deposit box or bank vault for long periods then it is advisable to put them in a sealed plastic bag with a little water or damp sponge to prevent them drying out. |
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We
supply a wide range unset Opal from all parts of Australia at very competitive
prices.
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