A purple pink diamond – the largest to ever appear at auction – is expected to sell for HK$195 million to HK$300 million (around US$25 million to US$38 million) at Christie’s Magnificent Jewels sale in Hong Kong.

The 15.81-carat fancy vivid purple pink internally flawless type IIA “Sakura Diamond” is one of the highlights of the live event, scheduled for May 23.

Fancy colour diamonds are among the rarest and most valuable gemstones, according to Christie’s. In particular, pink colouration in diamonds is caused by the distortion of the molecular lattice, which happens at random – making pink diamonds extremely challenging to cut from their rough form.

As fewer than 10 per cent of pink diamonds weigh more than one-fifth of a carat, this pink diamond is of an unprecedented size of 15.81 carats, which is the largest of its kind to be offered at any auction, explained the company.

Vickie Sek, chairman of the Department of Jewellery at Christie’s Asia Pacific, said Christie’s has offered some of the largest and rarest pink diamonds in history, including “The Winston Pink Legacy,” sold in Geneva in 2018 that still holds the auction record per carat for any pink diamond. 

Citing data from the Gemological Institute of America, the auction house said only 4 per cent of pink diamonds possess a colour deep enough to qualify as “fancy vivid.” The Sakura Diamond is graded as such for its perfect display of strong saturation and remarkable pink hue with a secondary purple colour.