Rare ‘fancy vivid pink’ diamond from Mwadui Tanzania sells for Sh133.9 billion in Hong Kong

An extremely rare “fancy vivid pink” diamond from Mwadui Tanzania has sold for Sh133.9 billion (£52m) in the process setting  a world record for the highest price per carat for a diamond sold at auction.

According to the UK’s Guardian, the 11.15-carat Williamson Pink Star diamond, which is named after another pink diamond given to Queen Elizabeth II as a wedding gift, was sold to an undisclosed buyer at auction by Sotheby’s Hong Kong on Friday, October 7.

Williamson owned the Mwadui mine in Tanzania is where the Williamson stone and the Pink Star were discovered.

Tobias Kormind, the managing director of London jewellery shop 77 Diamonds, said the stone’s link to the late monarch is likely to have helped elevate its value.

“This is an astounding result, proving the resilience of top diamonds in a shaky economy,” he said. “When you consider an alluring link to Queen Elizabeth, the rising prices for pink diamonds thanks to their increasing rarity, and the backdrop of an unstable global economy.

“Some of the world’s highest quality diamonds have seen prices double over the last 10 years.

The cushion-shaped diamond is named after two other large pink diamonds: the 59.60-carat, mixed-cut, oval Pink Star diamond that sold at auction in 2017 for $71.2m (then £57m), and the Williamson stone, a 23.60-carat diamond given to the Queen by the Canadian geologist and ardent royalist John Thoburn Williamson in 1947.

Mounted as a floral brooch designed by Frederick Mew, of Cartier, in 1953, the Williamson is said to have been a favourite of the late Queen, who wore it on many occasions during her reign, including the silver jubilee.

Wenhao Yu, the chair of jewellery and watches at Sotheby’s Asia, said: “The discovery of a gem-quality pink diamond of any size is an extremely rare occurrence, something that – with the recent closure of the Argyle mine – seemed, until recently, highly improbable.”

Argyle, a Rio Tinto-owned diamond mine in the remote north of Western Australia, was closed in 2020 after 37 years of operation, during which it produced more than 865m carats of rough diamonds.

Pink diamonds are particularly rare among coloured diamonds and no one knows exactly how they become pink geologically.

“While nitrogen and boron are responsible for the vivid hues of yellow and blue diamonds respectively, there is no evidence that pink diamonds receive their colour from trace elements,” Sotheby’s said.

“Rather, the crystal structure of the stone selectively absorbs light as a result of an idiosyncratic lattice defect, which results in an unusual arrangement of atoms in the crystal. These happy anomalies occasionally cause pink graining in the diamond crystal – a perfectly brilliant display of imperfection.”