Dubai stop for rare pink diamond that could sell for $21 million

At 11.15 carats, the cushion-shaped gem is named in tribute to two other pink stones

A stunning pink diamond could sell for more than $21 million when it goes under the hammer in October, auctioneers Sotheby’s said on Wednesday.

The dazzling Williamson Pink Star, described as one of the world's purest, is going on a world tour to build up interest in the sale ― taking in Dubai, Singapore, Taipei and Hong Kong where the auction will take place.

Kristian Spofforth, head of jewellery at Sotheby's, said pink diamonds are "exceptionally rare in nature".

"You then add in the extra factors like it being over 10 carats, internally flawless and Type IIa, and you get right down to the pinnacle," he said, referring to a subgroup of the most chemically pure diamonds.

At 11.15 carats, the cushion-shaped gem is named in tribute to two other pink diamonds.

The Williamson Pink Star, described as one of the world's purest diamonds, is going on a world tour. Photo: Sotheby's

One is the Williamson stone — a 23.60-carat diamond given to Britain's Queen Elizabeth II as a wedding gift by Canadian geologist John Thorburn Williamson. Worn by the monarch in a Cartier brooch, it was discovered in his mine in Tanzania.

The other is the CTF Pink Star, a 59.60-carat oval mixed-cut diamond, which sold for a record $71.2 million at auction in 2017.

Sotheby’s are selling the gem in a standalone auction on October 5. Photo: Sotheby's

The Williamson Pink Star also originates from the same Tanzanian mine.

Top quality coloured stones are prized by the super wealthy and Mr Spofforth said he expected many bids for the gem when it is offered for sale in a standalone auction on October 5.

"We saw over the lockdown crisis and the Covid crisis that there is always demand for the rare and the beautiful in the world, and this is something exceptionally rare that I think will have plenty of bidders on the day," he said.