De Beers is halting production at South Africa’s biggest diamond mine, with gemstone prices falling thanks to slowing demand and increased competition from lab-grown stones. The Venetia mine produces 40% of South Africa’s diamonds. De Beers managed to prevent prices sliding in the 1960s after the discovery of major reserves in the Soviet Union, via clever marketing and what The Atlantic in 1982 called “the most successful cartel arrangement in the annals of modern commerce,” but the ever-improving quality of artificial diamonds — and Chinese consumers’ collapsing interest in luxury goods — has defeated it. The cost of the real gems has fallen 50% since 2022, and De Beers’ parent company Anglo American is looking to sell.