Rio Tinto's diamond production was down 10% in the fourth quarter of 2010, totaling 3.199 million carats compared to 3.536 million carats in Q3 2010.

Year-on-year results showed a much sharper drop in diamond production, with the company producing 28% fewer diamonds in Q4 2010 than in the corresponding quarter of 2009.

Broken down by project, the company's Argyle diamond mine in Western Australia – which produces 90% of the world's pink and red colored diamonds – saw a 7% decrease in diamond production for the quarter and a 36% decrease compared to Q4 2009. The Diavik diamond mine in Canada saw production for the quarter drop 13% from Q3 but was still up 1% compared to Q4 2009.

While diamond production was down for the quarter, Rio Tinto increased its production of coal, uranium, molybdenum, copper and gold in the period reported, as well as hitting a new quarterly production record for iron ore of 65 million tons and a new annual iron ore production record of 283 million tons.