An ultra-rare extraterrestrial black diamond will be auctioned off by Sotheby's Dubai next month. The diamond, rated at a record-breaking 555.55 carats, is ranked among the largest and toughest diamond ever discovered.

The diamond, dubbed "The Enigma," is believed to have originated from outer space and dropped on Earth millions of years ago. According to Sotheby's expert gemologist, the diamond may have been formed by a meteoric impact. The diamond is believed to be more than a billion years old.

Sotheby's said it expects the diamond to sell for at least $6.8 million when it finally hits the auction block next month. The diamond will officially be up for bidding from Feb. 3 to Feb. 9, and Sotheby's said it would be accepting bitcoin and cash for the diamond.

Naturally-occurring black diamonds, also known as carbonados, are only found in Brazil and Central Africa. Due to its size, the presence of carbon isotopes, and its high hydrogen concentration, gemologists believe The Enigma may not have been created naturally on earth.

 It is the largest known black diamond of its kind, according to the Swiss House of Gübelin and the Gemological Institute of America. The diamond was officially recognized by the Guinness World Records as the largest carbonado in existence in 2006.


To match its unique carat rating, the Enigma has been cut with 55 facets. Sotheby's says it was a technical feat to cut the diamond, given that it is one of the toughest diamonds in existence.

Sophie Stevens, a jewelry specialist at Sotheby's Dubai, said the cut of the diamond is based on the Middle Eastern palm symbol of the Khamsa, which represents strength and protection. The symbol also represents the number five, which is in line with the overall theme of the diamond.

In its official description, Sotheby's Dubai claims that the auction of the diamond will be a "once-in-a-lifetime opportunity" for a lucky bidder to own one of the rarest cosmic wonders ever discovered by humankind.

This will be the first time the diamond has ever been shown in public. Sotheby's said the diamond would first be put on display at the Dubai Diamond Exchange later this week. It will then be placed on display in Los Angeles from Jan. 24 to Jan. 26, before it will be sent to London. Sotheby's said the diamond had previously belonged to an anonymous owner. It is not clear how he had acquired the diamond or who had first discovered it.