Thursday, 17 April 2014

What gives a Boulder Opal its value?




We currently have a stunning range of Premium Boulder Opals in stock – each one brilliant and one of a kind. They are notably higher in price than our previous selections of Boulder Opals, so what is it that gives a Boulder Opal its value?

Boulder Opals are easily distinguished by their layer of solid brown ironstone left on the back of the stone. Boulder Opals are mined from large ironstone boulders under the ground. Thin veins of colourful opal forms in the cracks and fissures in these boulders which are cut into the stones we sell.

Boulder Opals usually have a flat surface or an undulating surface and are almost always cut in a freeform shape to maximise the size of the stone. The quality of the work of the opal cutter affects the value of the gem as it should be polished so that no scratches or imperfections are visible to the eye.

Boulder Opals are valued by their colour, the number of colours, size and coverage of flash (the play of colour, sparkle within the stone) with red being most valuable followed by violet, orange, yellow, green and blue. The intensity of colour, pattern and the clarity are also very important.

A stone with strong colour and a full spectrum range is generally more valuable than one with a predominantly red fire, which is more valuable than one with predominantly green colour which in turn is more valuable than a stone showing only blue colour.

In summary, when looking at an opal consider the following:

Brightness - How bright is the gemstone overall?
Spectral Range - What range of colours are visible in the play of colour?
Saturation - How pure and vivid are the colours forming the play of colour?
Direction of flash – Is the play of colour visible from multiple directions?
 
Tip:

When designing a piece of jewellery using freeform Australian Boulder Opals, spend some time looking at it in the sunlight and turning it different ways to determine which angle is best to show the play of colour it holds. Do you want to be able to see the flash or do you want it to appear brilliant to other people?

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