Sotheby’s in Geneva has sold a rare purple-pink diamond for CHF24.4 million ($26.7 million), a record price for such a colour and class at auction. The 14.83-carat jewel, cut from crystal mined in Russia in 2017, was called “The Spirit of the Rose”, after a ballet performed by the Ballets Russes and Vaslav Nijinsky in 1911. The hammer price of CHF21 million before commission was reached after just a few minutes, when it was bought by a telephone bidder who chose to remain anonymous, Sotheby’s said on Wednesday. Coloured stones have been greatly valued as an asset class by the wealthy in recent years, with top-quality pink diamonds especially prized, according to the Reuters news agency. The Argyle mine in western Australia, which had produced the world’s largest supply of pink diamonds, stopped production last week due to depletion. “The lucky buyer could well profit from prices soaring for pink diamonds in the coming years thanks to increased rarity,” Tobias Kormind, managing...