Lucara Diamond Corp. has unearthed the largest uncut diamond in recent history in its Karowe mine in Botswana, the Canadian company said on Thursday, beating its own record discovery from November 2015 that it struggled to sell for nearly two years.

The 1,758-carat diamond, larger than a tennis ball, weighs close to 352 grams (12.42 ounces), Lucara said in a statement. The stone is second in size only to the 3,106-carat Cullinan Diamond, recovered in South Africa in 1905.

The stone is the latest in a series of high-value recoveries for the company at Karowe. Since introducing its XRT diamond recovery technology, Lucara has recovered 12 diamonds over 300 carats, including a 472-carat and a 327-carat diamond in April 2018.

The 1,109-carat Lesedi La Rona, which Lucara recovered in November 2015, failed to meet its undisclosed reserve price at a June 2016 auction, putting pressure on the company's shares. British diamond dealer Graff Diamonds finally bought it for $53 million in September 2017.

Forbes reported late last year that Graff had created 67 finished gems from the stone.