• Rare blue-green diamond sells at record price in global auction
• The gem is considered one of the rarest classified stones in the world after being discovered in Africa

A rare blue-green diamond known as “Ocean Dream” has been sold at a global auction for more than $17 million, according to Christie’s auction house.

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The 5.5-carat stone is the largest of its kind ever recorded and was extracted in the 1990s from a mine in Central Africa.

The Smithsonian Institution has described it as one of only eight of the rarest diamonds in the world, due to its unique color and exceptional clarity.

Experts at Christie’s noted that such stones are extremely rare, particularly in sizes exceeding one carat.

The sale took place in Geneva, setting a new record for a diamond of this color in auction history, after competitive bidding from buyers around the world. The winning bidder chose to remain anonymous.

The diamond was previously exhibited at the Smithsonian National Museum of Natural History in Washington, D.C., as part of a rare gemstones exhibition after being cut from a rough 11.70-carat stone.