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
Jericho Diamond Mine on certain covenants of their investment agreement, but is working with Shear to find funding or a purchaser. The mine was developed, opened and operated by Tahera Diamond Corporation. The company was provided with CAN $35 million loan by Tiffany & Co. to assist in construction of the site, as part of a marketing alliance. The mine produced diamonds from 2006 to February 2008, and was Tahera's only mining operation. The company reported financial losses in 2007 due to operational difficulties, the high value of the Canadian dollar, high oil prices, and the short operating season of the Tibbitt to