One of the world’s largest diamonds has been found in Africa — a 442-carat rock worth as much as $18 million, according to experts. Gem Diamonds Ltd. discovered the gem at its Letseng mine in Lesotho, the company announced Friday.

“The recovery of this remarkable 442 carat diamond, one of the world’s largest gem-quality diamonds to be recovered this year, is further confirmation of the caliber of the Letseng mine and its ability to consistently produce large, high-quality diamonds,” Gem Diamonds CEO Clifford Elphick said in a statement.