Rappers Love Black Diamonds. What Is a Black Diamond?

If you’ve been listening to a lot of rap music recently you’re probably aware that the latest must-have symbol of conspicuous consumption is jewelry made up of black diamonds. One recent afternoon I was fucking around on the Internet with 2 Chainz’s line from “Mercy” about his “chain the color of Akon” bouncing around my head when it struck me that I had no idea what black diamonds actually are. Are they real diamonds? Some other kind of mineral that’s just benefitted from a clever rebranding campaign? A synthetic product developed in a lab in order to keep Rick Ross in a never-ending supply of exotic gemstones?

After digging around for a few minutes I found out that the black diamonds rappers are going bananas over are technically called “carbonado,” and that their current popularity has a little to do with the recent development of a way to cut and polish them to make them jewelry-worthy, and a lot to do with (I guessed it) a heavy marketing push. I also found out that there is a really solid looking theory that Earth’s carbonado deposits are actually one big chunk of debris left over from a supernova that happened eons upon eons ago and just so happened to collide with the Earth just in time—give or take a couple of billion years—for rappers to rap about them. So basically 2 Chainz is wearing shit that came from outer space.

The leading proponent of the “black diamonds come from a supernova” theory, and one of the biggest experts in the world on the subject of carbonado, is Dr. Stephen E. Haggerty, a South African born geophysicist and Fulbright scholar who currently teaches at Florida International University. He even has a mineral named after him. He’s also a really nice guy who insists on being called “Steve” and loves to talk about carbonado. After a couple of quick emails I got him on the phone to tell me about the extraterrestrial origins of your favorite rapper’s favorite mineral.

VICE: So what exactly are black diamonds and how are they different from regular diamonds?

Stephen Haggerty: There are distinctions among black diamonds. There are the so-called true black diamonds, which are diamonds in every sense of the word, except that they’re black. These are largely but not exclusively from the Urals in the former Soviet Union, in Russia. The second type are carbonado, which are not known apart from two localities on Earth, namely Bahia in Brazil and the Central African Republic. I ought to add that there’s been over 600 tons of diamonds that have been mined, polished, cut, traded, stolen, and embellished on various body parts since about 1900. But not a single carbonado has been found in any of those mines. So there are these two spots on Earth, the Central African Republic and Bahia in Brazil, and at one point in time those two continents were joined. Geologically and geographically that’s one piece of real estate. And that’s the one place on Earth where carbonado is found.

[Other kinds of] black diamonds have been found in conventional kimberlite [a type of volcanic rock that often contains diamonds], not all over the world, but in many places. They’re described as black diamonds, and the blackness is due to inclusions of various types. Some are black graphite, some are iron ore, magnetite in particular and hematite. The carbonado has very exotic inclusions, but that’s not the reason that it’s black. In fact it’s not always black. It can be hues of blue and violet, red and slightly green. Black diamonds from the Urals or from some other kimberlites from around the world, those are readily cut and easily polished. Carbonado can be cut, but can only be cut by a laser, and it’s proprietary so even I don’t know how it’s done, but there are polishing techniques apparently that allow carbonado to be polished.  

So at one point this area in Brazil and this area in Africa were connected. How along ago was that?

So the continents broke up about 180 million years ago. But it turns out that the two pieces of real estate, which are one spot, actually go back in Earth history to about 3.8 billion years ago. So these two small pieces of continent floating on the Earth and moving around, they were essentially one piece of the crust on the Earth, and it was on this one piece of crust that I suggested that this meteorite, which is carbonado, landed. That’s really an important point, because this is one really small piece of crust. Just to put it in perspective, if I may, if it is a meteorite—and that’s what I’m proposing—we have to accept that the Earth in comparison to other planetary bodies in our solar system, and our solar system in the galaxy, and the galaxy in the universe, that our Earth is a very, very small target. People commonly say, well that sounds pretty extraordinary, and it is, so why don’t we see carbonados coming down in meteorites today? After all, the Earth is being bombarded by several tons of meteoritic material from the zone between Jupiter and Mars every day. But not a single carbonado has been recognized among them. What I’m proposing is the reason, since it’s just pure carbon it’s prone to ignition. At four billion [years ago] the Earth had a very thin atmosphere that was devoid of oxygen, and without oxygen it won’t burn.

In a large-scale way the Earth is a very small target, and the window of opportunity before it got this thick, oxygen-heavy atmosphere—it may have just been a cosmic stroke of luck that we got struck by this particular meteor.

The fact that the carbonado survived is indeed truly extraordinary. Now, it’s robust, it’s tougher—it’s not harder, and I don’t like the word but it’s an engineering term that is used to describe the strength of materials—it’s much tougher than regular diamond, because it doesn’t have an easy breaking direction. So it’s an ideal material for use in diamond drills, for example, and in fact I might add it was used in the construction of the Panama Canal at the beginning of the 20th century. Carbonado consists of very fine crystals that are randomly oriented, but glued together by diamond. This random orientation of the crystals, together with the fact that the interface is diamond, which makes it extraordinarily tough. But in addition to that the carbonado is porous, so it’s rather like a sponge. And there’s no diamond that’s ever been recognized, apart from carbonado, that’s porous. Moreover, the porosity is incompatible with the very high temperatures and pressures that are required to form diamond. To form diamond on Earth we have to go down to at least 180 to 200 kilometers—that’s 120 miles—down, vertically, into the Earth to reach a point in temperature and pressure where carbon will transform into diamonds.

There’s another way of producing diamond aside from high temperatures or high pressures, which was recognized in the late 70s and early 80s, and that’s that it’s possible to precipitate very small diamonds at low pressures but at very high temperatures–we’re talking about plasma, 2000 degrees centigrade rather than about 1000 for regular diamonds—and the environment is in a vacuum. So you get a vacuum chamber, strike a spark of plasma in there, and diamonds are precipitated. So it’s thought that this is the way that diamonds are formed in outer space—they’re formed by supernova explosions. In the early days when they started to look out into the cosmos using spectrometry the only material that they could identify that were particularly associated with supernova explosions was diamond.

Essentially these black diamonds that rappers are talking about may have come from supernovas.

That’s correct.

It seems like you’ve dedicated a lot of your career to carbonado. How does it feel to see it become a pop culture phenomenon all of a sudden?

Oh my golly. For it to reach the mainstream is enormously satisfying and gratifying. But I have to add, not everyone accepts the theory. The question is, what will settle it? Well I have two tests. One is for a meteorite to be seen—not to be found, but to be seen to fall, and it’s a carbonado. That would be the icing on the cake. The second would be to use astronomical observation into the asteroid belt, to look at those materials and to see whether there is a spectroscopic signature that’s diamond. If that’s the case then that would be carbonado.

Did you ever think that you’d end up sharing this interest in carbonado with rappers?

No, but I’m delighted. I’ve had to consult with my students, but particularly as I understand it, the rap culture is largely but not exclusively Afro-American or African. That’s particularly attractive to me, because one of the only sources is the Central African Republic. And I’m an African, although a different flavor.

@milesraymer