Where Do Diamonds Come From?

The industry’s proposed solution to the “conflict diamond” issue will cost millions of dollars, require untold hours of time and effort, and needs the approval of governments around the world-with nongovernmental organizations (NGOs) castigating the industry all the while for not acting fast enough.

It would be a lot easier if there was a way to determine the origin of diamonds.

Just about everyone who’s studied the question agrees it’s impossible to positively identify a diamond’s origin. But some, like Congressman Tony Hall (D-Ohio), doubt that the industry really cannot tell. Others-like ABC’s PrimeTime Live-have used it as a way to clobber the industry. For example, after De Beers’ Tim Capon claimed De Beers doesn’t buy “conflict” gems, ABC reporter John Quiñones nailed him with the question, “If I sat here and showed you a diamond from Sierra Leone and one from Botswana, could you tell the difference?” (De Beers says it can make that guarantee because it uses stones only from its own mines and no longer buys on the open market.)

Last year, British NGO Global Witness published a white paper with eight pages of citations it claimed “clearly [prove] that it is possible to identify diamonds.” Industry spokespersons note that many of these quotes date back to the turn of the century, when there were fewer diamond mines than there are today. (Since the industry agreed to the “certification” scheme, the group no longer makes this claim in public statements.)

Everyone’s getting into the act. In the past, there was little need for a way to determine diamond origin, but now the question has taken center stage. De Beers is researching the subject, as is Antwerp’s Diamond High Council (Hoge Raad voor Diamant, or HRD), Australian mining company BHP, and even the Royal Canadian Mounted Police, who are looking for a way to prevent smuggling from Canadian mines. And in January, the White House Office of Science and Technology held a conference on “Technologies for Identification and Certification.” (See sidebar p. 103.) Officials there hope the National Science Foundation will ask for grants to fund further research on the topic.

But scientists aren’t sure whether all this will lead anywhere. A De Beers geologist recently told The Wall Street Journal that it may one day be possible to determine where a diamond is not from-which is the point of the exercise in the first place. “It’s definitely easier to say ‘no’ than ‘yes,'” agrees Mark van Bockstael, director of international affairs for Antwerp’s HRD and head of its “conflict diamond” research. “You may be able to say ‘this stone is not from Angola,’ but when you ask where a diamond is from, it’s probably not possible [to answer that question].”

Van Bockstael predicts it will take five years before scientists know what can be done and five more to compile the necessary database. The Gemological Institute of America is also skeptical, but it, too, is re-examining the issue. “We wouldn’t rule out one day finding a method, but there’s no reason to think there will be a solution soon,” says director of research James Shigley. Still, he thinks that, even in the best-case scenario, many diamonds will remain unidentifiable.

One of the reasons there’s been confusion over this issue is that “diamond origin” can mean any of three different things: the origin of a parcel of stones, the origin of an individual piece of rough, or the origin of a polished diamond.

Of the three, determining the origin of an unsorted parcel of diamonds from a mine is considered possible-even easy-for experienced rough-hounds. Rough from the same mine has the same “skin,” and experts can spot a mine’s production by noting everything from the size of stones to the range of colors. De Beers has such expertise in determining “run of mine” that it’s volunteered to examine parcels of rough for customs offices.

But while De Beers may be able to identify parcels to its satisfaction, that may not be enough to satisfy legal authorities. “Suppose De Beers comes in and says ‘this is a parcel from Sierra Leone,’ and the government confiscates it,” van Bockstael says. “If someone confiscates your parcel, of course [you] would take the government to court. How can De Beers, or another expert, possibly prove that’s a parcel of Sierra Leone diamonds? The defense would get five experts testifying it’s something else.” He suggests stationing the experts at the office of the exporting country: “If you are looking at a limited group, it may be easier to say ‘this is a rebel parcel, and this is not.'”

However, smugglers can easily get around this by including diamonds from different mines. Mixing and matching is common even among scrupulous dealers to make parcels more salable. “A large parcel of rough diamonds from one source produces a coherent picture,” De Beers noted in testimony before the House Committee on International Relations. “Once that picture is broken up, it’s like a jigsaw puzzle with many missing pieces.”

The colored stone solution? The optimal solution is to base identification of an individual diamond’s origin on its chemical composition, which is how gem labs pinpoint the origin of certain colored stones. But determining colored stone origin isn’t foolproof-it’s possible to distinguish the locale of some stones but not others, and GIA doesn’t do origin tests because of concerns over their accuracy. “[Colored stone origin] is not an exact science and can more reasonably be characterized as professional opinions based on the best evidence available to date,” says GIA president William E. Boyajian.

There is anecdotal evidence that experienced traders can tell diamonds apart. One Antwerp dealer told newswires that he can guess with “90% certainty” the origin of any stone: “I can tell you Angola, I can tell you Sierra Leone, I can tell you Venezuela.” Still, these are nonscientific-though educated-guesses, which, again, may not pass legal muster. “Diamond dealers are not scientists,” van Bockstael says. “Sure, if they’re looking at all African stones, they may know which comes from where, but can they tell the difference between Canadian diamonds and the others? If they can, I’d like to see it.”

Diamonds are considered hard to identify because they’re formed in the earth’s mantle, which is the same around the world. By contrast, colored stones are grown in limited local environments. Also, diamonds are more than 99% carbon, so they don’t give scientists much to “play” with. “Diamonds are very clean,” says Dr. George Rossman, a professor of mineralogy at California Institute of Technology. “They don’t have variable environments of iron or chromium, like a lot of the colored stones do.” While there are low levels of non-carbon trace elements-which some scientists believe may provide a telltale “fingerprint”-there’s no evidence that these elements indicate where a diamond was mined. “The preliminary finding we have is that, even in the same kimberlite, the variations can be staggering,” van Bockstael says.

Locating these trace elements requires a technique known as laser ablation inductive coupled plasma mass spectrometry (LA-ICP-MS)-in plain English, drilling a microscopic hole in the diamond, then analyzing the material with a plasma mass spectrometer. “The procedure leaves a small crater in the stone, and it’s not something you could apply to polished stones,” says Ray Halwas, director of diamond projects for the Royal Canadian Mounted Police. “You could do it with rough if you knew how the stone would be polished.” But even this method is at present too expensive and time-consuming to be done on a regular basis: Each analysis takes hours to complete.

Rossman is looking at one easier solution: He’s found that certain diamonds have varying levels of hydrogen isotopes-which could possibly be indicative of the rainfall or waterway where the stone is found. But he says that once the diamond is acid-cleaned, this evidence could disappear. Even so, at the White House conference, most thought this area could be a promising one for future research.

People also are looking at age dating-which also requires expensive equipment-and examining the stones’ inclusions. One study, for instance, found higher degrees of sulfide in inclusions in diamonds from Sierra Leone-one of the key “conflict” areas. Still, determining this requires destroying the diamond-and experts don’t think this method could ever be done “in the field.”

Even if a method is discovered, there’s a logistical problem: Any research on diamond origin requires “run of mine” samples from every major source in the world-at least 25 deposits. In all, there are nearly 50 diamond-producing countries. “No such collection exists of diamonds of known sources, and assembling such a collection would be expensive and time-consuming, assuming that one would be given access to all worldwide sources,” notes Shigley. Nevertheless, the Mounties are trying to acquire such a collection, and at the White House conference, experts called for the development of one. But complicating the situation is the political reality of what researchers are trying to determine. Not only do scientists have to pinpoint the diamond’s country of origin, they’re being asked to determine in what region that diamond was mined. And it’s no easy task to get geological samples in areas controlled by rebels.

Even if indicators are one day found in the stones, there’s still the problem of primary and secondary deposits. The country where a diamond is formed is not necessarily the country from which it was mined. Most diamonds in the “conflict” controversy are found in alluvial deposits, meaning they’ve washed up on shores, generally after being carried through waterways that run through several countries. “You could have diamonds come up through the mantle and cross the border into a country that’s in conflict, and it would show the signature of the original country, which could be a perfectly legitimate source,” Shigley says. In fact, that’s why stones from southern Angola-which is occupied by rebel group UNITA-look similar to diamonds from Namibia and South Africa.

Other times, rebel and government forces are on opposite sides of a river-which means they’re mining the same kimberlites. Also, ownership of mines in “conflict” countries often changes hands, from the rebels to the government and back again-so what may be an illegal locale today may not be one tomorrow.

If some are skeptical about determining the origin of a rough stone, there’s even less hope for determining the nationality of polished diamonds, as called for in Rep. Hall’s first two “conflict diamond” bills. “When you polish a stone, you remove more distinctive features, so there’s even less to look at,” Shigley says. On rare occasions, it’s possible to guess from which mine a polished stone may have hailed-for instance, diamonds from South Africa’s Premier mine are known for their blue fluorescence, so much so that milky diamonds are called “Premier-ish.” But otherwise, determining the origin of a polished stone is considered all but hopeless.

Despite the obstacles, many expect diamond origin research to be a hot area in years to come. Halwas is more optimistic than most that this activity will bear fruit. “Right now, this is all conjecture and largely hypothetical, but there is promise,” he says. “It’s going to take years, but it’s never too late to get started. It would certainly solve a lot of problems.”