A semi black opal is very grey area (a joke). What determines a black opal and a semi black?
A black opal is an opal with a darkness scale of N1 or N2
A semi black is an opal that has a darkness of N3 to N4.
Semi blacks are a loose term for an opal that has a grey body tone and with opal colorplay on the top of the grey.
If your budget is not so high a grey or semi black opal can be a great substitute. The opal will still be brilliant and bright but at half the cost. Semi blacks are found in the same areas as black opal and can even be found in the same pocket underground.
There has been a larger market for semi blacks in the United States, but since the economy crash the idea of a semi black opal is more inviting to the opal merchant. The common term for semi black is a bluff stone. (Trying to pass to be a black opal)
Bluff stone have been used throughout the world by many opal dealers to try and bluff potential customers into thinking that that the stone is close enough or similar to a black opal.
Semi black have also been an opal that has been sent to China to be calibrated for ease of setting in jewellery. It’s price point is such that loss of carat weight is not as much of an issue than with black opal.
Some semi blacks have reached prices of over $4000 per carat on the opal fields.
Boulder opal is another producer of semi black opal with some ironstone being lighter in color giving the opal a lighter body tone to the gemstone.
Semi blacks are still considered precious gemstones. Only opal with no color called potch is called semi-precious stone.
Most semi black opal comes from Lightning Ridge in seam and nobby form.
For more information on opal cutting or purchasing opal. Please email blackopalsdirect@live.com or you can call me on Skype My username is Blackopaldirect and it's free!
