Black Diamonds – Everything You Need to Know
Black diamonds are as real as white diamonds but are not as common. It should be noted, though, that there are diamonds whose color has been artificially changed to black. There are, however, genuine black diamonds that occur naturally. Natural black diamonds, also called “carbonado”, can only be found in Brazil and Africa.
Although these stones have the same chemical composition as white diamonds, their crystal structure is different and they have many inclusions, causing them to differ in color.
There are different hypotheses as to how black diamonds were formed – some say that they were created within the earth under high pressure; others think that they came from space, on an asteroid that fell to earth some 2 million years ago.
Lab-made black diamonds are created by treating white diamonds with heat or radiation. As a result, the color of these stones was changed. Treated black diamonds are more common as the naturally occurring ones are relatively rare.
How Are Black Diamonds Graded?
The 4Cs – color, clarity, cut and carat weight – together with GIA’s International Diamond Grading SystemTM are the standards by which colorless to near-colorless (D-to-Z color diamonds) are graded. Black diamond’s fall outside this color range, so their color is evaluated based on GIA’s color grading system for colored diamonds.
What’s more, because black diamonds are opaque – and, in most cases, heavily included – they cannot be graded on the GIA clarity scale. Likewise, because there is no variation in the tone and saturation of a black diamond (unlike their pink, yellow, or blue counterparts), only the single grade term Fancy black is used. Consequently, GIA does not issue grading reports for these diamonds. Instead, GIA issues a Colored Diamond Identification and Origin Report. In this report, such diamonds are described as Fancy black and their color is noted as either natural or treated.
Black Diamond - 5 Fast Facts
Black diamonds are tougher than any other diamond. They are a 10 on the Moh’s hardness scale and their dense polycrystalline structure makes them more difficult to cut and polish than colorless diamonds.
Black diamonds don’t shine in the traditional sense. Black diamond’s actually absorb light instead of reflecting it, meaning their beauty comes from their surface which is polished like marble.
Larger black diamonds are actually made up of millions of other smaller black crystals. Traditionally, diamonds are a single, solid stone, but black diamonds are bound together by internal inclusions that hold millions of smaller pieces together.
It can take up to a year to cut a black diamond! Because these natural precious gems have an unusual combination of carbon and graphite atoms, such a mix robs them of uniform crystallography. Therefore, in order for a cutter to assure a beautiful black stone, the diamond cutting process for these black gems can be frustrating and time-consuming.
Some black diamonds started out green. How? Some gem dealers irradiate green diamonds, for extra-long periods of time, in order to ensure that the stones have an ebony-like color. While irradiation can achieve that, you want to be sure to ask if the black diamond in the ring you’re buying has, in fact, been irradiated. Because, as a customer, you should always know exactly what you’re buying.