Rio Tinto reports that its diamond production for the fourth quarter of 2013 totaled 4.498 million carats, a 38 percent increase in volume year over year and an 8 percent increase in volume compared to the third quarter of 2013.

Fourth Quarter

At the miner's wholly owned Argyle mine in Western Australia, rough diamond production for the fourth quarter, totaling 3.153 million carats, was 57 percent higher year over year, reflecting increased tonnes processed in the period and higher grades following commissioning of the underground operation at the end of April, which will extend the life of the mine until at least 2020. Compared to the third quarter of 2013, production was up 2 percent.

The miner's share of diamond production from the Diavik diamond mine in Canada's Northwest Territories, of which it holds a 60 percent interest, totaled 1.240 million carats in the fourth quarter, up 9 percent compared to the corresponding quarter in 2012. According to Rio Tinto, the rise in carat recovery was a result of an increase in tonnes processed as the underground mine ramped up to full production, which was partially offset by lower grades. Production was 24 percent higher than the preceding third quarter of the year.

At the Murowa mine in Zimbabwe, of which Rio Tinto owns a 78 percent stake, production rose 7 percent year over year and 51 percent quarter over quarter to 105,000 carats.

Full Year 2013

For the full year of 2013, Rio Tinto saw a year-over-year increase of 22 percent in rough output to 16.026 million carats. At Argyle, production grew 34 percent to 11.359 million carats, while at Diavik Rio Tinto's share of production remained flat for the year at 4.346 million carats. Murowa output grew by 3 percent to 322,000 carats.