The "rare and extraordinary stone... means so much in the context of diamonds and Botswana," she said. "It brings hope to the nation that is struggling."
It also the biggest stone of gem quality to be recovered in the history of the company, a joint venture between the government and global diamond giant De Beers.
The biggest diamond ever discovered in the world was the 3,106-carat Cullinan, found in South Africa in 1905.
The second largest was 1,109-carat Lesedi La Rona -- a diamond the size of a tennis ball, discovered at Karowe, northeastern Botswana, in 2015.