An exceptional 1,305-carat diamond was discovered in the Karowe diamond mine in Botswana on Monday, according to the tenement's Vancouver-based owner.

"The recovery of our 10th diamond exceeding 1,000 carats is another extraordinary milestone for Karowe," William Lamb, Lucara Diamond president and chief executive officer, said.

"No diamond mine in history has consistently produced diamonds of this magnitude and Karowe continues to set itself apart on the global stage," he added.

Unfazed by a slump in market prices and demand, Botswana continues to stand as one of the world's leading diamond producers, prolific for sourcing exceptionally large diamonds vital for various uses, including jewellery cutting.