The world's largest known cut diamond went on public display for the first time Monday ahead of its sale, when it is expected to sell for $5 million.

"The Enigma," the name of the rare black carbonado diamond, was put on display in Dubai, in the United Arab Emirates (UAE).

The diamond is believed to have been created when a meteorite or an asteroid hit the Earth more than 2.6 billion years ago, according to Sotheby's auction house jewellery specialist Sophie Stevens.

One of the most difficult substances to cut, the 555.55-carat diamond has never been shown by its unnamed owner of the past 20 years, but experts turned it into a 55-face jewel.

Its shape was inspired by the Middle East palm-shaped symbol of power and protection, the Hamsa, which is also associated with the number five.

"It is very different," said Stevens of the jewel, which holds a Guinness World Record as the largest cut diamond.

After being on show in Dubai "The Enigma" will also be taken to Los Angeles and London, before a seven-day online auction starts on Feb. 3.

What Sotheby's called a "cosmic wonder" could very well go to a bitcoin bidder, Stevens said.

"We are accepting cryptocurrency for the diamond, which we have done for other important stones," she said.

Last year in Hong Kong, the "Key 10138" diamond sold for $12.3 million, which was paid in cryptocurrency.