A Boulder Opal Bracelet - Total Weight 46.5cts. Natural Opals and 1.11ct. Smaller Diamonds
Lot No. ：CCJD-OB-180707
Feature： Natural blue sapphire *, 18k gold and yellow diamonds.
Weight：46.5cts. sapphires, 1.11ct diamonds, 48g gold.
* Australian Boulder opals are the second most valuable type of opal (following black opal). Boulder opals, as the name suggests, are mined from large ironstone boulders under the ground. Thin veins of colourful opal forms in cracks and fissures in these boulders. Because these veins of colour are so thin, opal cutters need to leave the ironstone on the back of the opal to form a full sized stone. The thin layer of opal in boulder opals can display any colour of the spectrum in a beautiful play of colour. A 'clean faced' boulder opal, in which a whole bar of colour is visible on the surface of the stone, is much more desirable and valuable than a surface displaying ironstone spots.
Valuing boulder opal per carat is not generally accepted in the industry due to the large component of ironstone present in the stone. However, to give a rough indication, top quality boulder opal may fetch prices of up to AUD $3,000 per carat for a gem quality stone. A clean faced stone with no ironstone spots is generally more valuable than a spotted stone.
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