GABORONE, Aug 22 (Reuters) - Canada's Lucara Diamond

Corp ( LUCRF ) has dicovered a 2,492 carat diamond at its Karowe

mine in Botswana, the company said late Wednesday, one of the

largest stones to be excavated.

Lucara did not reveal the stone's gem quality but its size

would make it the second largest rough diamond discovered to

date, after the 3,106 carat Cullinan Diamond found in

neighbouring South Africa in 1905. After being cut and polished,

it became part of the British crown jewels.

The Karowe Mine is known for producing large stones, with

other significant finds including the 1,758 carat Sewelô and the

1,109 carat Lesedi La Rona diamonds.

The company will present the diamond to Botswana's President

Mokgweetsi Masisi on Thursday. Botswana is the world's top

diamond producer by value.

The southern African country last month proposed a law that

will ask mining companies, once granted a licence, to sell a 24%

stake in mines to local investors unless the government

exercises its option to acquire the shareholding.