LONDON – A uncommon, dazzling pink diamond is predicted to promote for an estimated $21 million when it goes up for public sale in October, officers stated. 

The 11.15-carat cushion-shaped stone, known as the “Williamson Pink Star,” was described by public sale home Sotheby’s as “one of many world’s purest, most saturated pink diamonds.” 

The diamond was named after two different notable pink diamonds, together with the record-breaking CTF Pink Star, a 59.60-carat oval mixed-cut diamond, which bought in 2017 for $71.2 million. 

The Williamson Pink Star was additionally named in homage to the celebrated “Williamson” stone, a reduce diamond of 23.60-carats given as a marriage current to Queen Elizabeth II in 1947. It was gifted to the queen by Canadian geologist and royalist, Dr. John Thorburn Williamson, who owned the Williamson mine in Mwadui, Tanzania, the place it was found.

The Williamson Pink Star additionally originates from that mine in Tanzania, Sotheby’s stated.

A mannequin holds the Williamson Pink Star in a supplied picture. (Credit score: Sotheby’s)

“The invention of a gem-quality pink diamond of any dimension is a particularly uncommon incidence – one thing that, with the current closure of the Argyle mine, appeared till just lately – extremely inconceivable,” Wenhao Yu, chairman of jewellery and watches at Sotheby’s Asia, stated in an announcement.

“Pushed by a restricted provide and rising demand, costs for top-quality massive pink diamonds over 5 carats have elevated exponentially over the previous decade, serendipitously setting the scene for the looks now of this one-of-a-kind stone,” Yu added. 

The Williamson Pink Star is pictured in a supplied picture. (Credit score: Sotheby’s)

What precisely makes the Williamson Pink Star diamond so uncommon?

Pink is without doubt one of the rarest colours to happen naturally in diamonds, based on the public sale home. 

“With its distinctive coloration, appreciable dimension, and dazzling sensible reduce, the Williamson Pink Star is each a piece of nature and a murals, establishing its place among the many most fascinating coloured diamonds,” the Gemological Institute of America (GIA) stated in an announcement. The GIA is a nonprofit cited by the public sale home as a number one supply of data and requirements on diamonds.

The Williamson Pink Star is pictured in a supplied picture. (Credit score: Sotheby’s)

Of all of the diamonds submitted to the institute, lower than 3% are categorised as coloured diamonds. And of these, lower than 5% are thought of predominantly pink, based on Sotheby’s. Narrowing in additional, solely the tiniest proportion of pink diamonds have a robust sufficient coloration to be categorised as “Fancy Vivid Pink,” which the Williamson Pink Star is classed. 

“A Fancy Vivid Pink diamond, weighing over 10 carats is subsequently of the utmost rarity. Not solely has the diamond obtained the best color and readability grades, it has additionally been discovered to be a part of the uncommon subgroup comprising lower than 2% of all gem diamonds – generally known as Sort IIa. Stones on this group are chemically the purest of all,” Sotheby’s stated. 

The Williamson Pink Star was unveiled on Wednesday at Sotheby’s London and can embark on a world tour, going to Dubai, Singapore, and Taipei earlier than arriving in Hong Kong, the place it will likely be bought in a single-lot public sale on Oct. 5. 

This story was reported from Cincinnati.