Rio Tinto's diamond production dropped in the first quarter of 2011.

The company's Argyle mine in Western Australia – the source of 90% of the world's pink and red colored diamonds – yielded 1,641,000 carats in Q1, a 35% drop from the corresponding quarter of 2010. The drop of in carat production reflected lower ore grade. In addition, the company noted that due to heavy rains in March 2011, 14% fewer ore was processed during the quarter than in Q1 2010.

Canada's Diavik diamond mine, in which Rio Tinto holds a 60% stake, produced 812,000 carats in Q1, down 13% year-on-year. While the amount of ore processed at Diavik increased 25%, carat recovery dropped due to the lower grade ore mined in the A418 open pit.

Rio Tinto's 78% owned Murowa mine in Zimbabwe produced a total of 45,000 carats during Q1. Murowa's total production for 2010 stood at 139,000 carats.

In total, the company's diamond mining operations – which in 2010 produced a total of 13,843,000 carats – yielded 2,498,000 million carats in Q1.