This pink diamond sold for a historic record of $18 million

This pink diamond sold for a historic record of $18 million

Coloured diamonds are now the world’s most expensive precious rocks.

A fancy 8.41 carat, pear-shaped, flawless pink diamond sold for a record $17.8 million in Hong Kong this week, over $3m more than what Sotheby's was expecting to fetch, setting a world auction record on a per-carat basis for this kind of gems.

The auction house did not reveal the buyer's identity, but said than 200 people attended the bidding at the Hong Kong Convention and Exhibition Center in Wan Chai.

This pink diamond sold for a historic record of $18 million

The most expensive vivid pink diamond ever sold.

Internally flawless clarity is extremely rare in pink diamonds, and the auction house said this, in combination with its "fancy vivid" colour grading, made the stone "amongst the rarest and most desirable of coloured diamonds ever seen at auction".

Pink diamonds are rare, and only one in 10,000 of mined diamonds qualifies as the sought-after “fancy” or “intense” grade, according to GIA, the jewels institute.

Coloured diamonds shortage has helped push diamond prices up, to the point that these rocks are now the world’s most expensive stones. A 14.82-carat orange diamond sold for $36 million at Christie’s International in Geneva in November, setting a record $2.4 million a carat. The same month, Sotheby’s sold the Pink Dream, a 59.6-carat pink stone, for $83 million.