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
Jwaneng diamond mine of waste rock. The mine is located on three kimberlite pipes that converge near the surface, covering 520,000 square metres at ground level. Currently, the mine produces approximately 11 million carats (2,200 kg) of diamonds. The recoverable ore grade at the mine is about 1.25 carats per ton (250 mg/t). , known reserves will allow production at current levels to continue for 27 years. The high rate of diamond extraction, combined with high quality diamonds fetching excellent per weight prices, make the Jwaneng diamond mine the richest diamond mine in the world by value of recovered diamonds. Jwaneng employs over