A spokesman for Sotheby's said the diamond, which sold for $1.32 million per carat, broke the previous record, held by a red diamond, the "Hancock Red," which went for around $900,000 per carat in 1987.
The diamond was bought by Moussaieff Jewelers to add to its already large collection of rare gemstones. The seller was a private Asian collector.
Blue diamonds, whose distinctive color is due to a trace amount of boron in the stones, are extremely rare. The Hope blue diamond, currently held at the Smithsonian Institution in Washington D.C., is the largest in the world, at 45.52 carats.