Small rock, big diamond

Like all mega-diamonds, the multimillion-dollar lump of perfect carbon that has just emerged from a mine in Lesotho, southern Africa, is not much to look at. Just a couple of inches long, it weighs 478 carats, which is just under 100 grams, or three and a bit ounces.

The 20th largest diamond discovered in history, the find was announced on Monday, though the rock was unearthed on Sept 8 at Letseng, the same mine which has produced two other monsters in the past two years. Respectively the 17th and 18th largest diamonds in history, they weighed in at 603 and 493 carats.

The government of Lesotho, the minority shareholder in the mine, named the first the Lesotho Promise and the second the Letseng Legacy.

The latest diamond – the Lesotho authorities have yet to exercise their naming rights – has been tucked away by Gem Diamonds, the mining company which has the majority share in Letseng, in a vault in an undisclosed location, probably in Antwerp, Belgium, the centre of the world diamond trade.

Because of its unremarkable size, one could easily mislay the stone, which would be annoying because even in its present state this rough diamond, awaiting cutting and polishing, is worth upwards of US$10 million (Dh36.7m). Depending on the advice of the cutting experts, the diamond could yield a single giant gem or a series of smaller stones, worth between $40m and $60m.

If it became a single gem, the final product, says Gem Diamonds, could weigh up to 150 carats, which is 30 grams, or one ounce. Because of its existing structure it would be round and would be the largest such gem in the world.

For context, a forerunner is the Koh-i-Noor diamond, reputed to have been discovered 5,000 years ago in India and swathed in so much legend that it is priceless; also round and 105 carats, which until recently had been thought remarkable. It has been part of the British Crown Jewels since Queen Victoria became Empress of India in 1877.

Clifford Elphick, the chief executive of Gem Diamonds, said: “Preliminary examination of this remarkable diamond indicates that it will yield a record-breaking polished stone of the very best colour and clarity.”

Glenn Turner, 47, a director of the international company who is based in London, was even more enthusiastic: “It is absolutely top, top class. It is as good as you get. It is flawless.”

Stones like this one, said Mr Turner, explained why diamonds had entranced mankind over the centuries. To the Greeks they embodied strength. Plato thought diamonds were living spirits. The Romans called them “tears of the gods”. Many have believed that diamonds possessed magical qualities, to heal or to bring great luck, or misery.

The likely buyer of the Lesotho diamond will be one of the world’s elite jewellers, who have built multibillion-dollar empires based on their relationships with the super-rich. These include Britain’s Laurence Graff, reportedly worth £1.5 billion (Dh 9.75bn) and the UK’s 36th richest person. One of his aides said that Mr Graff, believed to be in his late 60s – he is famously coy about his age – would inspect the diamond personally in Antwerp before deciding whether to bid for it.

“He will know immediately if he wants it,” said the aide. “He has seen so many fantastic diamonds over the years that he won’t need any advice.”

Precedent suggests there will be a sealed-letter auction, with Graff Diamonds outbidding rivals. If that happens, Graff’s experts will then spend months analysing the diamond, using computers and hi-tech scanners, similar to those used in medicine.

Only when they are sure they have established the best and safest way to cut the stone will they actually touch it. It is likely to take a year, possibly longer, to transform the rough diamond into a magical gem or gems. In the process, it will lose much of its weight – probably around 70 per cent – during the cutting and polishing. Then it would be shipped to London for the company’s designers to conceive a suitably gracious display form, such as a necklace.

There is a slim chance that the cutting of the Lesotho stone – which even with today’s technology is risky, since a tiny miscalculation would wreck the diamond – could take place in Dubai, which is fast emerging as a rival to the traditional diamond centres of Antwerp, New York and Tel Aviv.