Rio Tinto today reported that it produced 4.27 million carats of diamonds during the quarter ended December 31, 2015, a 50% increase over production in the same quarter a year earlier. This was largely on account of the huge year-on-year increase in production at Argyle, which produced 3.7 mn carats as a result of the ramp up of underground production.

However, Q4 production at Argyle was marginally below the production in the earlier quarter as a result of process plant pauses to manage inventory levels, the Company said.

At Diavik, where the company has a 60% share, carats recovered in the fourth quarter were three per cent lower than the same period of 2014 due to lower processing volumes largely offset by higher recovered grades. However, production was 18% above the levels reported in Q3 2015.

Rio’s total volume of diamond production for 2015 stood at 17.39 million carats, a 25% increase over its production of 13.87 mn carats in 2014.

The company said that the ramp-up of production from the underground mine delivered at Argyle resulted in a 47 per cent increase in carats produced compared to 2014.

At Diavik, carats recovered were 11 per cent lower than in 2014 due to processing plant pauses in the fourth quarter and the absence of stockpiled ore which was processed in the first half of 2014.

The company sold its stake in the Murowa mine in Zimbabwe in mid-2015.