diamond color ?

yes. They are either heavily included stones with surface reaching fissures which are often heated to make them go blacker.
Or irradiated (lower quality) stones that are so dark green they appear black. These are tougher and usually used in pave settings

Hi all,

Color is the most critical factor affecting the price of any gem variety at a given size. Color can be separated into three basic components: hue, saturation, and tone. Diamond color actually becomes desirable - such as yellow diamonds, black diamonds, or pink diamonds - are not judged in the same way. For the color grade, the range of G-I usually offer a good value, Because the price is somewhat lower than that of an otherwise equivalent diamond with a higher color grade.

Thanks.
George Rowe

I was researching diamond colour grading for the purposes of purchasing an antique stone, and I found this, which I thought might be of interest to folks in this thread


http://www.ruby-sapphire.com/crying-game.htm