![]() A true harlequin pattern is extremely rare and highly sought after. Harlequin, large sections of colour in which each colour segment is roughly the same size and shape, like a mosaic or chequerboard.The distinctiveness and colour displayed by these segments determines the quality of the pattern of an opal. The pattern of coloured segments, forming the play-of-colour of a precious opal, is unique to every individual opal. This ranges from brilliant, bright, to subdued or dull.Ībove – left to right, brilliant, bright, and subdued. Brillianceīrilliance refers to the brightness and clarity of the colours displayed by opal, when the stone is viewed face-up. Red colouring is caused by larger microscopic silica spheres, whereas blue is caused by the more common small spheres. Nature does not produce a red colour as often as it does a blue or green. Red (fire) opal is generally more valuable than a mainly green opal which, in turn, is more valuable than a stone showing only blue colour. The phenomenon known as the “play-of-colour” is the brilliant range of the full spectrum of colours caused by the diffraction of white light by the internal structure of orderly arrayed spheres of silica. ![]() ![]() (See image, below) Some crystal opal displays colour so intense, so dark, that the opal is referred to as ‘black crystal opal.’ Black Opal Semi Black Opal Boulder Opal Crystal Opal White OpalĪbove – Black Opal, Semi-black Opal, Boulder Opal, Crystal Opal, White Opal The play of colour The term crystal opal refers to the ‘diaphaneity’ (transparency) of an opal, not its crystal structure, and is defined as any type of opal which is translucent to transparent. White opals have a light body tone and are generally the least valuable form of opal. Boulder opals also have a dark body tone. Generally opals with a black or dark body tone are more valuable than those with a white, light, or crystal body tone, because a stone with a darker body tone tends to display colours more vibrantly.īlack opal is the most prized opal and may realise prices over AUD $15,000 a carat. Body tone refers to the background or the ‘underlying colour’ of the opal, which ranges from black through dark to light. Body Toneīody tone is one of the most important factors in the classification and valuation of opals. Doublets and triplets are an ‘assembled’ stone which only contains a very thin slice of natural opal and are therefore generally much less valuable. An opal doublet or triplet can be worth considerably less than a solid opal. Opal classįirst of all, it is essential to identify the type of opal which is being valued. The overall carat size of the stone will then determine the price of the opal. When being valued, opal is carefully examined and given a price ‘per carat’. Other important factors include the quality of the cut & polish, and the size of the stone. The type of opal, body tone, brilliance, pattern, colour bar thickness, the play of colour, and faults all play important roles in determining the value. The value of an opal depends on many factors. FAQ : How is opal valued? What makes a good opal? What are the different patterns in opal? What faults can opal have that detract from its value? What is the play-of-colour? What should I look for in a good opal? How are opals valued? Why are some opals more expensive than others?
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