A black-and-yellow dump truck rumbles up from a giant pit in the mountains of southern Africa, carrying a load of freshly blasted slate-gray rock from the Letseng mine. With luck it will contain a golf-ball sized diamond worth perhaps $20 million. With even more luck the stone won’t get smashed.
Keeping giant gems intact during the mining process is a challenge for the two companies that account for most of the global production of these multi-million dollar whoppers. They’ve unearthed 15 of the 20 largest diamonds found in the past decade. Almost every one lost a chunk at some point in the process, including a stone called the Lesedi La Rona that is the largest found in more than a century.
“Since the time of the caveman mining hasn’t changed much. You pulverize the rock and take out what you want,” said Clifford Elphick, chief executive officer of Gem Diamonds Ltd., which runs Letseng. “That’s fine in the metals business, but in the diamond business it’s not an appealing technique.”
Gem Diamonds, which operates Letseng in the small kingdom of Lesotho, and Lucara Diamond Corp., which opened its Karowe mine in Botswana in 2012, are in a very different business from De Beers, the world’s biggest producer. With large stones their core business, rather than an unexpected windfall, they’re trying new scanning technologies to reduce accidental breakage.
Back at the mine, Thaabe Letsie watches the truck ascend the open-cast pit under a clear winter sky, pauses from directing four drilling machines and says the mining process is a long way from the glamor of the end product.
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