How is Opal Valued?

Before you buy opals online, you should have a fair idea of how opals are valued. It can help you make an informed choice. It is quite difficult to make out how much an opal is worth, just by looking at the pictures online. An honest dealer will allow you to return an opal or will give you more details on the stone. The opal should have been objectively graded and should come with a certificate of authenticity. Here are a few details on how opals are valued.

Opal Class

The first thing you should look for is the class. There are basically three classes of opals- solid opals, doublet opals and triplet opals. Doublet and triplet opals contain only a thin slice of precious opal and so are cheaper than solid opals.

Type of solid Opal

If you want to buy a solid opal, then the major factors that you should consider are the body tone, weight of the stone and pattern and brightness of the stone.

Body Tone of the Opal

The body tone is the most important factor in the valuation of an opal. Based on the body tone, there are three types of opals. They are black opals, semi-black opals and light opals and these are measured on a scale between N1 and N9. Generally, the darker the body tone, the more valuable the opal. So black opals are more precious than semi-black opals, which are in turn more valuable than light opals.

The Flashes of Colour in the Opal

The flashes of colour in the opal is also called 'play of colour'. The flash is created when light hitting the opal gets diffracted. A stone with a red/orange flash is more valuable than a stone with a green flash, which is again more valuable than a stone with a blue flash.

Brilliance or Colour Clarity

The brilliancy or clarity of the colours of the opal is also taken into consideration when valuing the opal. This can range from brilliant, subdued to dull.

The Pattern of Colours

A precious opal will have some unique coloured segments. The colour displayed or the distinctiveness of the pattern will also determine the value of the opal. The most common patterns are harlequin, flagstone, ribbon, straw, Chinese writing and picture stones. Other patterns are floral, rolling flash, broad flash and pinfire.

Some other factors like the colour bar thickness and faults (if they exist) are also considered to decide the value of the opal. Note that the best opals come from Australia, which produces 90 percent of the world's supply of opal. You may be tempted to buy an opal on eBay or a similar site where the prices might be unbelievably low. But there is no free lunch and there is chance that the dealer may actually be quoting the price for a synthetic opal or a doublet or triplet opal. It is best to buy opals from a well known dealer.