DUBAI, United Arab Emirates—Auction house Sotheby’s Dubai has unveiled a diamond that’s literally from out of this world. Sotheby’s calls the 555.55-carat black diamond—believed to have come from outer space—“The Engima.” The rare gem was shown off on Monday to journalists as part of a tour in Dubai and Los Angeles before it is due to be auctioned off in February in London. Sotheby’s expects the diamond to be sold for at least 5 million British pounds ($6.8 million). The auction house plans to accept cryptocurrency as a possible payment as well. Sophie Stevens, a jewelry specialist at Sotheby’s Dubai, told The Associated Press that the number five bears an important significance to the diamond, which has 55 facets as well. “The shape of the diamond is based on the Middle-Eastern palm symbol of the Khamsa, which stands for strength and it stands for protection,” she said. Khamsa in Arabic …