Rio Tinto released its production results for the quarter ending December 31, 2018 and the full year, reporting a 15% drop in diamond production in 2018 as compared to the previous year. The drop was largely on account of the expected lower carat production at its Argyle mine in Australia, which is nearing the end of its productive mine life.

Total production for the year, inclusive of Argyle (100% owned) and its share of the Diavik mine (60% owned) stood at 18.4 million carats, as against the 21.6 million carats produced in 2017, the miner reported.

A major decline as seen in Q4 2018, which saw production dip by 40% over the same period a year earlier, and by 12% over the previous quarter. The drop was mostly on account of Argyle, where annual carat production was 18% lower than in 2017, and where Q4 production fell by 47% to 3.21 mn cts as compared to 6.15 mn cts a year earlier. Rio Tinto said that this was because production in 2017 was enhanced by the processing of higher grade alluvial tailings.

At Diavik, carats recovered in 2018 at 4.36 mn cts was 3% lower than the 4.49 mn cts recovered in 2017. The marginal drop was attributed to lower recovered grade, which was partially offset by higher ore processing. The A21 project successfully mined first ore in March 2018 and reached commercial production during the fourth quarter.

Rio Tinto said that production guidance for 2019 was between 15 and 17 million carats.