A pink diamond sold for a record-breaking $17.77 million at Sotheby’s Hong Kong on Tuesday.

The auctioneer said the Fancy Vivid 8.41-carat gem was the rarest and most desirable of its kind to be seen at auction because of its “remarkable” purple-pink hue and internally flawless clarity “virtually unseen in any significant pink diamond ever sold at auction.”

Diamonds in the Fancy Vivid category are considered as having the highest possible concentration of color.  The record-breaking diamond has been mounted onto a ring by Sotheby’s Diamonds.

The stone, as big as a thumbnail, had “attracted keen competition” before the hammer went down, said Quek Chin Yeow, the Deputy Chairman and Head of Sotheby’s Asia’s Jewellery Department. The final price of $17.77 million is well over the high estimate of $15.5 million.

Holding the previous world auction record for a Fancy Vivid pink diamond was a 5-carat stone that sold for $10.77 million in Hong Kong in November 2009.

Also setting a new record at the October 7 auction was a 17.6-carat Kashmir sapphire and diamond ring that achieved the most expensive sapphire price per carat, at $236,404 per carat. The ring sold for a total of $4.06 million.