Valuation
Opal valuation has been stated to be the most difficult of all types of gemstones. It was Richard T Liddicoat, then President of the Gemmological Institute of America who made the statement “if opal and diamond were placed on a (valuing) grading scale from 1 – 10 then diamond would be the easiest at number 1 and opal the most difficult at number 10”.
Valuing of precious opal and precious opal jewellery is indeed not an easy thing to do. Jewellery valuing is a different type of science and a technical skill that requires much time and effort to master. The basic principals for valuing jewellery and gemstones are laid out by the National Council of Jewellery valuers (NCJV) and come down to a number of considerations. The most important principle is that any opal or piece of opal jewellery must be valued into or according to the market into which the item is going to be valued. While all precious opals whether rough pieces and parcels or cut and polished gemstones all have a potential value, it is important realise that real value is probably only determined when the opal has been traded, this translates into the commercial aspect of how many dollars are actually exchanged for the piece of opal that is being sold. Opal is like any other commodity, a transaction takes place between a willing buyer and a willing seller. This establishes a “price”. However there are some differences a between the “price” and the “value” of an item. Valuers should always talk about “value” and not “price” in my opinion.
The NCJV reflects this by using the terms “purpose and function”. Any valuation must have a purpose, what will the valuation be used for and a function, or which market is the valuation representing.
While this is not an expansive discussion regarding valuation procedures, some of the purposes of a valuation will include a valuation for replacement (where and item has been lost) or a valuation for disposal ( where an item has to be sold and money obtained for it). These valuations will be different in their actual dollar value.
Markets are not all easy to define, however a few suggestions can be made at this time. For opal there is a market on the field where the opal has been mined, people will talk about a “field price” (or a field value!). There is a different market like much jewellery that is a “wholesale market” where an opal has been purchased previously and is then offered for sale to perhaps a jeweller who will use it to make a piece of jewellery. There is also a “Retail market” where an opal or a jeweller/jewellery store will offer the item for sale to the consumer. Each of these markets will have a different dollar value.
But let us look at opal from a gemstone point of view first of all and there are several things that make opal evaluation difficult:
Opal is seen with a Play-of-colour (precious opal) and without a play-of-colour (Ornamental opal or common opal)
Opal is seen in all ranges of body colour all the way from black through greys to white, and sometimes with a slight overtone.
Opal is also seen in different “body colours, for example yellow, orange ,and red (Mexican Fire Opal)
Opal is also seen in most other body colours as well, examples are blue, green and pink (from Peru), brown (Tintenbar NSW)
Opal is seen in all ranges of diaphaniety from transparent to opaque.
Opal is seen with “cat’s eye” chatoyancy and “stars” asterism.
Opal often has a special uniqueness
The four “C’s” for evaluation of gemstones are the same for Precious opal and refer to the Colour, Clarity, Cutting and Carat weight of the opal concerned. So let us consider these parameters.
COLOUR
In this discussion we will spend our time discussing precious opal, the first on the list above, and later we will consider other varieties of opal.
Examining the colour potential for an opal is likely to be the most difficult part of an assessment for any single opal. The difficulty comes from the most important attribute of precious opal and that is its Play-of-colour sometimes referred to as “POC” if you like the use of acronyms!
The Play-of-colour in precious opal is difficult to evaluate and the reason for this is because every opal is unique in its colour, no two opals are exactly the same. If we make a comparison for, example, with other gemstones, say a diamond, I can match two diamonds of the same quality without too much difficulty, or I can match the colour of two rubies or sapphires so that they match. With opal it is much more difficult.
Also when considering how to value a precious opal a most important thing to remember is that we are going to examine how the opal looks in the “face up” position, or to use the appropriate opal industry term, we are going to look at how the opal “faces”. This is also not a random consideration, in order to gain an understanding of how an opal “faces”, you have to move it around! An opal must be viewed in many different directions in order to let the gemstone tell you its story, the key is movement.
So there are a number of parameters for consideration in evaluating a precious opal not listed in any particular order of preference these parameters for consideration are:
What is the body colour or body tone of the opal (or what is the over all background colour, is it Black, Dark or Light)
Brightness or vividness (simply put how bright or vibrant are the colours)
What colours are actually visible in the opal? (are there red colours, or blues and greens, and which one predominates)
What is the pattern like? (How are the colour grains arranged? Is the pattern distinct, or random, is it special)
Is the pattern consistent over the face? (are the colour grains the same size, shape, arrangement?)
Are the colours consistent in their brightness? (are there different bright spots or dull spots in the pattern?)
CLARITY
Clarity of gemstones can be a difficult discussion to have as it generally considers information regarding imperfections in gemstones. Good gemmologists and jewellery valuer’s in most instances describe these imperfections as “inclusions” in a gemstone. Unfortunately in some instances these imperfections are called “flaws” which in many ways is a derogatory term. Many inclusions though are very small things that a gemstone possesses that actually allow a gemmologist or a scientist to learn more about the gemstones origin and formation. Rather than being bad, many inclusions are good, and they point us towards the “natural” origin of the gemstone or piece of opal.
However this fact aside, it is apparent that the clarity of a gemstones often affects the value in a relationship that says the more imperfections, then the lower the value. Certainly imperfections such as fractures, cracks and similar breakages can have a detrimental effect both on value and the function of the gemstone.
CUTTING
For jewellery purposes most gemstones are fashioned, or cut and polished in a way that makes their natural attributes more beautiful and more useful for setting into items of jewellery. There are many different parameters for cutting precious opal, and those people who know how to cut opal and produce quality gemstones have special talents in being able to transform a rough piece of opal into a spectacular gemstone. The ability of an opal cutter should never be underestimated.
Most Precious opal is cut “en cabochon” or in a domed fashion in order to bring out the special features of colour and pattern. Some more transparent varieties of opal are faceted (usually these gems are without a play-of -colour, but not always), and faceting is making inroads to some play-of-colour (POC) opal. More recently and especially with “boulder opal” free form cutting has become much more important.
Among the parameters that are considered from a value point of view are items such as the shape of the opal, is it an oval shape or a round shape for example. What are the proportions of the opal like? What is the quality of the “polish” and how has the opal been “finished”?
Over many years the market preferred “oval” cut gemstones for jewellery use. Cutting oval stones can be more wasteful for the amount of opal available in the rough. However more recently there has developed a desire by some innovative opal cutters to use the rough more economically and to carve opal into different shapes, undulations and even figures.
CARAT WEIGHT
Last but not least in the consideration of value and evaluation is how big is the finished opal gemstone? Gemstones are almost always sold by weight, and the weight used is the standard “metric carat”. One carat is simply one fifth of a gram. Another way is to say that a carat is 200 milligrams.
Still some different methods are used in some markets. Much Queensland Boulder opal is sold at a price “per piece” rather than per carat.