Rio Tinto reported an 87% rise in diamonds recovered from the Argyle mine in Australia in the second quarter of this year. The increase reflected "increased tons processed and higher grades from the underground mine which was commissioned in April 2013," the firm said in a financial report.



Meanwhile, at the Diavik mine in Canada's NorthWest Territories where Rio has a 60% stake, there was a 13% decline in carats recovered from the second quarter of 2012 as a result of lower grades of ore mined during the quarter. Rio reported that the transition to a fully underground mine at Diavik was successfully completed in June, with production from all three kimberlite pipes underway.



At its Murowa mine in Zimbabwe where Rio has a 78% holding, there was a 21% rise in production compared to the year before, equaling 69,000 carats.