Williamson Pink Star: rare diamond sells for $49.9m in Hong Kong auction

A rare, fancy, vivid pink diamond has set a new world record for the highest price per carat for a diamond sold at auction.

The 11.15-carat Williamson Pink Star, sold for $49.9 million at auction in Hong Kong on Friday. The jewel was purchased by an undisclosed buyer.

Certified as “internally flawless” and “fancy vivid” — the highest grade of coloured diamond available — the piece sold by Sotheby's is named after another pink stone gifted to the late Queen Elizabeth II.

It is only the second pink diamond of this calibre and weight to come to auction.

Yielded from a 32-carat rough diamond at the Williamson Diamond Mine in Tanzania, the gem was on display at Sotheby’s Dubai in September, where experts had predicted it would sell for more than $21m.

The final asking price fetched in Hong Kong was more than double those estimates — the diamond's total sale price was just shy of $50m, or $57.73m inclusive of auction fees.

Wenhao Yu, chairman 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. Driven by a limited supply and rising demand, prices for top-quality large pink diamonds over 5 carats have increased exponentially over the past decade, serendipitously setting the scene for the appearance now of this one-of-a-kind stone.”

Only two fancy vivid pink diamonds are known to be larger than this one, and of those only one has ever appeared at auction.

The CTF Pink Star, an oval-shaped fancy vivid pink stone weighing a monumental 59.60 carats, was sold at auction in April 2017 for $71.2m, setting a world record for the “most expensive diamond, gemstone or jewel”, that still stands five years later.

The other stone will never come on to the market, as it was gifted to Queen Elizabeth II as a wedding present in 1947. Weighing 23.60 carats, it was presented by John Thoburn Williamson, the owner of the Tanzanian mine where it was unearthed.