A pink diamond was sold for a record 57.7 million US dollars in Hong Kong, AP reported.

This is the highest price achieved per carat for a diamond sold at auction.

The 11.15-carat Williamson Pink Star stone was sold by Sotheby's in Hong Kong.

At close to US$5.2 million per carat, it surpassed the previous record of US$4 million per carat for a blue diamond sold in 2015.

The buyer is a private collector from the US, Sotheby's announced.

Williamson Pink Star is named after two legendary pink diamonds.

The first is a 23.40-carat "Williamson" pink diamond that was a wedding gift to the late Elizabeth II in 1947. The second is a 59.60-carat "Pink Star" that sold for a record $71.2 million at auction in 2017

The Williamson Pink Star is the second largest diamond sold at auction.

And it, like Queen Elizabeth II's diamond, is from the Williamson mine in Tanzania.

The mine is known for its pink diamonds, which are among the rarest and most valuable of the colored diamonds.

According to experts, some of the highest quality diamonds have doubled in price in ten years.