Largest flawless blue diamond sells for nearly $24M

The largest flawless blue diamond ever sold just went under the hammer at Christie's for nearly $24 million.

The 13.22-carat gem was expected to sell for between $21 million and $25 million, so the sale was within the expected range.

The stone was the top lot at Christie's Magnificent Jewels sale Wednesday, where 250 lots were expected to sell for a total of about $80 million.

Source: Christie's Images Ltd. 2014

Last year there were two notable diamond sales. Christie's sold "The Orange"—the largest fancy vivid orange diamond in the world—for $35.5 million.

Then, in November, Sotheby's Geneva auction house sold the "Pink Star" diamond for a record $83 million—$23 million above the asking price. But the auction house was later forced to buy back the gem after the buyer defaulted.

More auction news:
Warhols auctioned for more than $100M
Most expensive Rolex sells for $1.2M

—By CNBC's Robert Frank.