The Fancy Vivid Blue Diamond Ring broke the auction record which had stood for 20 years, according to a Sotheby’s spokeswoman, fetching US$1.32 million for each of it 6.04 carats.

The price for the emerald-cut piece smashed the record held by the Hancock Red, a red diamond which was sold for US$926,000 per carat, Sotheby’s said.

Monday’s purchase — which was clinched by Moussaieff Jewellers in London, a specialist in rare stones — was part of the auction house’s autumn Hong Kong sale, which includes Chinese ceramics and contemporary art.

The entire jewel sale fetched US$40.84 million, including US$2.64 million for the “Irving Berlin” emerald, a long 47.60 carat necklace previously owned by the celebrated U.S. composer and lyricist.