The 1,109-carat stone, which is said to be 2.5 to 3 billion years old, was bought by British diamond dealer Graff Diamonds for $47,777 per carat on Monday. It will now be cut and polished, Lucara said in a statement.
It had originally hoped to get at least $70 million for the stone, describing it as the biggest gem quality diamond found in more than a century, CBC News reported.
The new owner, Laurence Graff of Graff Diamonds, said becoming the "custodian" of the diamond was the highlight of his career.
"The stone will tell us its story. it will dictate how it wants to be cut and we will take the utmost care to respect its exceptional properties," he said.
The only larger diamond previously unearthed was the 3,106-carat Cullinan Diamond, which was discovered in South Africa in 1905. The Cullinan was eventually cut into smaller stones, some of which are now part of British royal family's crown jewels.