Speaking to Anadolu Agency, Binani said the "Sotheby's "will be offering this absolutely unique object of art and something that is much more than a jewel, with no reserve for purchase at cryptocurrency.
"We are very excited to mention that this diamond has been recorded … as one of the largest fancy black diamonds and also the largest cut diamonds ever to be recorded and known in the world," she added.
The Enigma was listed as the world's largest cut diamond by the Guinness Book of World Records in 2006.
Unlike most diamonds formed deep within Earth, carbonados are found in alluvial, sedimentary deposits, close to or on Earth's surface, the auction house explained.
"This, and their specific mineral make up suggest possible extra-terrestrial origins, either from meteoric impacts producing natural chemical vapor deposition or from diamond-bearing asteroids colliding with the Earth."
The diamond "surpasses the weight of both the Great Star of Africa, 530.2 carats, and the Golden Jubilee, 545.67 carats, making it not only one of the largest fancy black natural-color diamonds in the world, but also the largest faceted diamond to ever appear on the auction market."