Debswana Diamond will invest $3.7bn to extend the life of its Jwaneng mine in Botswana.
The funds will add seven years to mine life and secure another 102 million carats of diamond production from the mine, located 100 miles west of Gaborone.
According to Bloomberg, Debswana Diamond general manager Balisi Bonyongo has said that the primary mine development project is 20% complete and will be fully completed by the end of 2011.
Bonyongo added that the extension project would also mine 658 million tonnes of waste material to allow for underground mining in the future.
Debswana Diamond is a joint venture between De Beers and the government of Botswana.
Botswana is expected to produce 24 million carats of gems in 2010, up 36% from 2009.