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
Argyle diamond mine ore and acid washed, they are sorted and shipped to Perth for further sorting and sale. A significant quantity of diamonds are cut in India, where low costs of labour allow small diamonds to be cut for a profit; this is especially relevant to the Argyle mine, which on average produces smaller rough diamonds than other mines do. The diamonds produced at the Argyle diamond mine are of an average low quality. Only 5% of mined diamonds are of gem quality, compared to a worldwide average of 20% (Author Janine Roberts contends that the "near-gem" quality rating is subjective and