Image: Enigma – Sotheby’s

The Enigma, a 555.55 ct. fancy black diamond that is considered the largest cut diamond ever brought to auction, has been sold by Sotheby’s London for 3.1 million pounds sterling—approximately $4.3 million, seemingly below expectations.

The 55-facet diamond was sold as part of a single-lot online auction Feb. 3-9. It was sold without a reserve, and the company did not provide a public estimate. However, the BBC reported that the diamond was expected to fetch $6 million, or 4.4 million pounds.

In a tweet, the auction house announced that “the buyer has opted to use cryptocurrency for the purchase.

While the auction house did not announce the buyer’s name, cryptocurrency entrepreneur Richard Heart, founder of several crypto trading platforms, announced on social media that he had purchased the diamond.

On Twitter, Heart said that once he takes full possession of the diamond, it would be renamed diamond, after one of the blockchain platforms that he founded.

It’s a match made in Heaven,” he said in a video, noting that many of the platform’s users have 5,555 tattoos, as that’s the maximum amount of days a Hex stake can be locked up for.

The Enigma has been listed as the largest fancy black natural diamond in the world, according to the Gemological Institute of America and Gübelin Gem Lab. In 2006, Guinness World Records called the Enigma the largest cut diamond in the world.

Its shape and design were inspired by the hamsa, a Middle Eastern hand-shape symbol that is a sign of protection, power, and strength, the auction house said.

Black diamonds, often called carbonados, are known only to be found in Brazil and the Central African Republic. Some scientists feel that these stones are created either from a meteor or a diamond-bearing asteroid that crashed into Earth.