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Opal
Pricing Guide & Buying Guide Tip 1. Under nearly all circumstances if a certain opal appeals to you that is the one you should buy.Often our intuition is the best judge! Tip 2.When purchasing opal some key words to look for are : A. Opal Triplet a very thin slice of opal enhanced by blackening the underside of the opal to make the colors stronger and a quartz or plastic dome placed on top of the opal to magnify the color and pattern. The advantage is they are cheap and fit readily into standard size jewelry. B. Opal Doublet a thicker slice of opal with a blackened underside. The advantage over a triplet is the surface is real opal and affords a greater depth of color. C. Solid as the name suggests a real and solid opal with no add-ons. Therefore A has less value than B which has much less value than C when size color and pattern are the same. Tip 3. Laboratory produced or treated matrix opal have far less value than triplets, doublets and solids. Tip 4. Solid opals come in many variations, if size pattern color and shape are the same the most valuable opal will be.
1.Black opal the rarest and most highly prized of all. The best black opal comes from Lightning Ridge, Australia. Black opal has very rich and striking colors that are formed on a dark or black potch base. This dark base intensifies the colour. Black opal has been sold for as much as $14,000 per carat wholesale or field price. Outstanding quality for $10,000 per carat field price. Black opal with all the colors and good quality starts at around $2,000 per carat on the field. The opal may go through many sets of hands before arriving in the retail shop and so the retail price is much higher. Top quality black opal is very rare and in relation to many other gemstones is probably under priced. The investment potential for even medium grades of black opal is very very interesting. This is a resource that is fast disappearing !
2. Boulder opal especially the darker variety. Boulder opal gets its name from the fact that an ironstone backing is part of its natural formation, the colors can also be quite brilliant and dazzling and gem quality also brings a high price almost matching the black opal prices. It would appear that there is a larger production and it is found over a much wider area (mainly Western Queensland ) than black opal and so the price of average grade material is somewhat lower.
3. Crystal opal or Fire opal. This variety of opal can also be extra ordinarily beautiful and gem material can sell for $1000 per carat wholesale or field price. This opal is translucent and even transparent when held up to the light. Lightning Ridge, Andamooka and Coober Pedy are all produces of gem materials. Thinner pieces of crystal opal make the best doublets and triplets.
4. White opal. Gets its name from the white potch the color forms on or in. Coober Pedy has produced very large quantities of white opal. This opal is much cheaper than the above mentioned varieties. This is partly due to some of this material being quite porous and brittle. However some white opal is still very attractive indeed and some of it is quite stable. 5. Water opal. I have left the Mexican water opal last, partly because it generally doesn't have the fire of the other opal families and partly because I haven't seen all that much of it. I have never been to the areas where it is produced, nor did I wish to leave this important category out. *Please note there are many opal fields in the world but because 90% of the World's production comes from Australia I have concentrated on them. Brazil, U.S.A., Honduras and Indonesia also produce opals. Tip 5. Brightness of color, play of co lour ( what the co lour does when you move the stone ) general appeal including patterns or pictures and co lour combinations are all determining factors when valuing an opal. When these factors are the same then red will be the most valuable, followed by pink orange gold yellow green and the blue and then purple. Part of the reason for this value scale is that purple is the most common and red the rarest. Just to put things in perspective though, an opal showing very bright or electric blue can be valued as highly as an average red opal all other things being equal ! Tip 6. Use your intuition!
Tip 7. When buying rough opal that is uncut opal on the internet, buy samples first if possible. If some of the rough is faced it makes the opal rough parcel far less risk. If you're buying opal on the opal fields try to find clues in the rough parcel. Most rough is sold wet so you can see the colors as they will be when they are polished. This is standard practice. However it pays to wipe a few bits dry as this will show up any crazing or cracks often caused from contact with jackhammers or bulldozers etc ! Faced pieces will show up the general character of the whole parcel usually. Opal miners don't mind you taking a good close look at their product, but if you find something you don't like be discreet. Never knock or rubbish some ones opal..... They've probably worked really hard for it and they won't like unkind comments and you won't like being hung upside down by one leg over a deep mineshaft either! Tip 8. Don't knock or rubbish miners opal......see tip 7! Tip 9. Making offers. Making an offer when buying opal is quite common these days on the opal fields. The miner has his price but will sometimes take a bit less. A little bit less than the asking price might make the difference to getting a good deal or a great deal. Making an offer that appears to be an insult to the miner might turn things upside down....see tip 7! Tip10. Opal miners are the best people to buy opal from. If you go to an opal field then opal miners are the ones to buy off. Often "wheelers and dealers" and people who "mine opal from the bar in the pub" will tell visitors don't buy off the miners they will rip you off. Think about it. The best deals come from the miners! If you want to buy fish the best buy is from a fisherman! Tip11. If your on an opalfield and the locals are a bit shy about who might have some nice opal for sale a few or quite a few cold beers produced from the vehicle your traveling in can indeed be liquid gold ! Tip12. Don't drink too many of them yourself ! Not until you made your purchase anyway. Tip13. Only necessary if you disregard tip12! Tip14. Money: Cash is the accepted way of purchase on the opal fields. However if you are wishing to buy a large amount of opals it is best to make arrangements with the local bank (Westpac Bank in Lightning Ridge) preferably a week in advance. Then you can use cash cheques which is fine for most miners and a lot safer than carrying large amounts of cash around. You will still need some cash as it is easier for small purchases. Unfortunately many opal fields don't have banks close by. Then its probably best to just "window shop" until you find the deal that you want. Most opal miners will travel to where there is a bank to make a reasonable sale. Generally the opal fields in Australia are safe places to do business, providing a little common sense is used. Other arrangements are often made with opal miners and I have seen buyers arrive in nice shiny four wheel drive vehicles and then trade them for a parcel of opal and a lift to the closest airfield. Please come back to this page again as I have many more Tips to come ! OPAL NOMENCLATURE AND CLASSIFICATION From the "AUSTRALIAN OPAL AND GEM INDUSTRY ASSOCIATION LIMITED. " Australian Gemstones: The Australian Gemstone Industry Council Inc., in collaboration with the Australian Gem Industry Association Ltd., the Gemological Association of Australia Ltd., the Lightning Ridge Miners Association Ltd. And the Jewelers Association of Australia Ltd., has produced the following nomenclature for the classification of opal. OPAL CLASSIFICATION Opal is a gemstone consisting of hydrated amorphous silica with the chemical formula SiO2.nH2O. There are two basic forms of opal described by visual appearance. Precious Opal - is opal which exhibits the phenomenon known as play-of-color, produced by the diffraction of white light through a micro-structure of orderly arrayed silica spheres to produce changing spectral hues. Common Opal and Potch - is opal which does not exhibit a play-of-color. The distinction between common opal and potch is based on formation and structure. Potch is structurally similar to precious opal but has a disorderly arrangement of silica spheres. Common opal shows some degree of micro crystallinity. TYPES OF NATURAL OPAL Natural opal is opal which has not been treated or enhanced in any way other than by cutting and polishing. There are three types of natural opal, with varieties described by the two characteristics of body tone and transparency. Natural Opal Type 1 - is opal presented in one piece in its natural state apart from cutting or polishing and is of substantially homogenous chemical composition. Natural Opal Type 2 - is opal presented in one piece where the opal is naturally attached to the host rock in which it was formed and the host rock is of a different chemical composition. This opal is commonly known as boulder opal. Natural Opal Type 3 - is opal presented in one piece where the opal is intimately diffused as in fillings of pores or holes or between grains of the host rock in which it was formed. This opal is commonly known as matrix opal. VARIETIES OF NATURAL OPAL The variety of natural opal is determined by the two characteristics of body tone and transparency. Body Tone The body tone of an opal is different to the play-of-color displayed in precious opal. There are three varieties of natural opal based on body tone. Body tone refers to the relative darkness or lightness of the opal when ignoring the play-of-color. Black Opal - is the family of opal which shows a play-of-color within or on a black body tone by reference to the AGIA Body Tone Chart N1, N2, N3 and N4 when viewed face up. Dark Opal - is the family of opal which shows a play-of-color within or on a dark body tone by reference to the AGIA Body Tone Chart N5, N6 when viewed face up. Light Opal - is the family of opal which shows a play-of-color within or on a light body tone by reference to the AGIA Body Tone chart N7, N8 or N9 when viewed face up. The N9 category is referred to as white opal. Opal with a distinct colored body (such as yellow, orange, red or brown) should be classified as black, dark or light opal by reference to the AGIA Body Tone Chart with a notation stating its color hue.
Opal shows all forms of diaphaneity and ranges from transparent to opaque. Natural precious opal which is transparent to semi-transparent is known as crystal opal. Crystal opal can have either a black, dark or light body color tone. The term "crystal" in this context refers to appearance not a crystalline structure. OPAL TREATMENTS Opal can be subjected to various types of treatment. Present CIBJO guidelines state that any method of treatment other than standard cutting and polishing must be disclosed and the process used specified on all invoices, advertising and commercial documents. Types of treatments include color enhancement, heating, painting, dying, resins and waxes, oiling or any application of chemicals. Opal is treated to change its natural appearance, structure or durability. Opal is color enhanced in opal inlay jewelry where usually a thin solid crystal opal has black paint or glue applied or set above black painted jewelry. COMPOSITE NATURAL OPAL Composite natural opal consists of natural opal laminates, manually cemented or attached to another material. The opal component is natural opal. There are three main forms of composite opal: Doublet Opals - are a composition of two pieces where a slice of natural opal is cemented to a dark base material. Triplet Opals - are a composition of three pieces where a thin slice of natural opal is cemented to a dark base material and a transparent top layer, usually of quartz or glass. Mosaic and Chip Opals - are a composition of small flat or irregularly shaped pieces of natural opal cemented as a mosaic tile on a dark base material or encompassed in a resin. SYNTHETIC OPAL Synthetic Opal is material which has essentially the same chemical composition and physical structure as natural opal but has been made by laboratory or industrial process. Synthetic composites exist as synthetic doublets, triplets or mosaics and must be disclosed as synthetic composites. IMITATION OPAL Imitation Opal is material which imitates the play-of-color of natural opal, but does not have the same physical and chemical structure or gemological constants as natural opal. CLASSIFICATION REPORTS Classification reports for the following types of opal should include these details: Natural Opal 1. Type of opal Treated Opal 1. Type of opal Composite Opal 1. Type of composite as doublet, triplet, mosaic or
chip opal Synthetic and Imitation 1. Gemological category including manufacturer (if
known) Origin Any indication of the origin of opal by the use of geographical locationshould not be used unless it is qualified as an indication of the type of locality only as recommended by the International Confederation of Jeweler, Silverware, Diamonds, Pearls and Stones (CIBJO) such as Lightning Ridge type black opal.
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