Large 555-Carat black diamond believed to be from outer space unveiled in Dubai; See pic

The largest known cut diamond in the world was put on public display for the first time on Monday ahead of its sale, which it is expected to reach five million dollars, NDTV reports.

The rare black carbanado diamond 'Enigma', went on public display in Dubai, UAE.

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

"To have a natural faceted black diamond of this size is an extremely rare occurrence and its origins are shrouded in mystery - thought to have been created either from a meteoric impact or having actually emerged from a diamond-bearing asteroid that collided with Earth," Sotheby's said in a statement.

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

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

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

After being on display in Dubai the Enigma will then travel to Los Angeles and London, before a seven day online auction begins on February 3.

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