A flawless fancy vivid pink diamond sold for a record $17.7 million in Hong Kong late Tuesday, Sotheby's said.

The auction house said the internally flawless 8.41-carat stone had been expected to go under the hammer for up to $15.5 million.

Quek Chin Yeow, deputy chairman of Sotheby's Asia, said the pear-shaped stone had "attracted keen competition before fetching a wonderful price of HK$137.88 million (US$17.77 million) and setting a world auction record for a fancy vivid pink diamond."