‘Purest, pinkest’ diamond expected to set new price record at Hong Kong auction

Auction house Sotheby’s says it is the second largest, internally flawless ‘fancy vivid pink’ diamond ever to go under the hammer.

The “one-of-a-kind” gem is among the rarest on Earth, with the intensity of its pink hue and its size making it stand out in the rare gem market.

It is named after two other huge pink diamonds, the Williamson Pink Diamond and the Pink Star. The former was gifted to then-Princess Elizabeth by John Thorburn Williamson, the owner of the Tanzanian mine it was found in, while the latter was sold at auction in 2017 for a record-breaking $71.2 million.

The Williamson Pink Star is unlikely to fetch quite so much – at 59.6 carats, the Pink Star is many times larger. However, with an estimated price of over €20 million, it looks set to break the per carat price record.

Pink diamonds are exceedingly rare. Only three per cent of diamonds graded by the world’s leading certifier, the Gemological Institute of America (GIA), are classified as coloured. Of these, less than five per cent are predominantly pink. Of this fraction, only four per cent creach the grade of Fancy Vivid Pink – and these are often small in size.

Exactly why some diamonds take on a pink colour is a mystery. Sotheby’s explains that “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.”

“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.”

Pink diamonds gained widespread popularity in 2002 when actor Ben Affleck proposed to star musician Jennifer Lopez with a 6.1-carat engagement ring featuring the rare stone.

They were further implanted in the public conscious through the 2006 film Blood Diamond, which saw actor Leonardo DiCaprio confront the realities of conflict diamonds.