This huge black diamond just sold for £3.1 million. No one knows where it came from.

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The Enigma: Mysterious black diamond up for auction

Rare diamond, blasted from outer space, could fetch $6.8M

A 555.55-carat black diamond believed to come from space is going on sale

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Black 555.55-carat diamond dubbed 'The Enigma' sells for £3.1 million at auction

Black diamond, largest ever cut, sells for £3.2 million

Black diamond, largest ever cut, sells for £3.2 million

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