This huge black diamond just sold for $4.3 million. No one knows where it came from.

Geologists still can't say for sure whether the enormous stone called the Enigma crystallized in Earth’s mantle or fell from outer space.

The Enigma.': Giant 555.55-carat black diamond heads to auction

Benitoite Gem Mine, San Benito County, California - Collectors Edge

Enigma Black Diamond Sells For $4.3 Million At Auction

The Second-Biggest Diamond in History Has a New Owner - The New York Times

The Enigma: Billion-year-old black diamond sold for £3.16m

This huge black diamond just sold for $4.3 million. No one knows where it came from., Black Diamond

Billion-Year-Old Black Diamond Sells for $4.3 Million - WSJ

The Enigma: Mysterious black diamond up for auction - BBC News

Are Lab Diamonds as Good as Real Natural Diamonds?