Does Opal Have a Standard Like Diamonds?
Question: Is there a standard like the colors D,E,F,G,H, etc. in diamonds where an opal stone is compared to a known standard?
Answer: There is a priority in the colors.
Basically - it goes Red..Royal Blue..Green.., in that order but....
there are so many combinations with the colors, you cannot pin it down to an exact science, unlike diamonds!
Color intensity, patterning and play of color all come into play. Usually though, the brighter the red, the more valuable the opal gem.
Even out at Lightning Ridge, a miner would take a valuable gem to three separate valuers to get an "average" on the worth of the opal gem as each valuer would price it differently - it just is that each individual will view it a little differently.
With regards to a Black Opal the N1 to N4 on the Opal Scale is the backdrop for the darkness tone, which then determines which category the stone may fall within.
Translucence is how far you can see down through the color layers.
As an example, on black opal, the gem bar may be very bright and sits on a black base but it may also be very translucent, enabling one to peer down into it's depths.
However, another black opal may have brilliant colors but may be much more dense in tone because of the depth of the black tone throughout the gem colors themselves, and you will not be able to see much further than the surface play of color - therefore it would be difficult to class it as translucent.
Carat for carat, color for color, the more brilliant and more tone dense the color (not necessarily translucent) then the more valuable the Black Opal would be.
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