The cushion-cut diamond, which is mounted on a ring, has been described by experts as “glowing” and has the highest ranking possible for the quality of colour, defined as “Fancy Vivid”. It has the top score for clarity, known as “Internally Flawless”, meaning that no blemishes are visible under 10x magnification. It’s among the most chemically pure of all diamonds, which contributes to its transparency.

5 timeless emerald high jewellery pieces for spring, from Gucci to Chaumet

The 2.1-gram gem is comparable to “ultimate masterpieces of art”, according to Sotheby’s, which said it’s more unique than a Rene Magritte or Andy Warhol painting. “It is difficult to overstate its rarity and beauty,” said Wenhao Yu, chairman of jewellery and watches at Sotheby’s Asia.

The Eternal Pink was mined by De Beers at the Damtshaa mine in Botswana. It took six months for artisans at Diacore in New York to fashion it.

Three pink diamonds feature in the top five diamonds by value ever sold at auction. They have become rarer since the closure of the Argyle mine in Australia, which was the largest supplier of the stones. Less than 3 per cent of all the diamonds submitted to the Gemological Institute of America are coloured and pink is the rarest of those.