Argyle diamond mine at the Ekati mine, both in Canada. However, Argyle has two to four times the concentration of diamonds (ore grade) of these mines. This makes extraction economically feasible, as mine costs are mostly related to the amount of ore processed, not the amount of diamond extracted. In 2005, Rio Tinto was given the go-ahead to a future expansion project, moving it from an open pit to an underground mine. This plan was postponed; in September 2010 Rio Tinto announced fresh plans to develop an underground mine beneath the existing pit, increasing annual production to 9 million tonnes of ore. The
Kelsey Lake Diamond Mine America. The gem was cut and polished by legendary New York diamond cutter Bill Goldberg which yielded a faceted stone that sold for $87,500. In July 1997, the company found two gem-quality stones weighing in at 16.3 carats and 28.2 carats. The 28.2 carat diamond was cut into a 16.86-carat stone, one of the largest finished stones ever produced in North America. The cut diamond is bigger than the gemstone produced from the "Uncle Sam" diamond, which was cut into a 12.42-carat stone. Kelsey Lake Diamond Mine Kelsey Lake Diamond Mine is a defunct diamond mine in Colorado, USA. It