Rio Tinto's diamond production in Q1 2019 declined by a total of 18% on an annual basis from its two mining operations in Australia and Canada due to lower recovered grade. The lower grade particularly affected diamond output at its 100% owned Argyle mine in Australia, where production fell by 22% year-over-year and 13% from the final quarter of 2018 to just under 2.8 million carats. Likewise, Rio Tinto's attributable output at its 60% owned Diavik mine in Canada (Dominion Diamond Mines own a 40% share) fell by 5% year-over-year and 6% from Q4 2018 to just north of 1 million carats, as lower recovered grades were partially offset by higher ore processing.
Total production achieved from both operations was 3.8 million carats, declining from 4.6 million carats in the same period a year ago and 12% from the 4.3 million carats recovered last quarter. Rio Tinto's diamond production guidance for 2019 is unchanged at between 15 and 17 million carats after having recovered 18.4 million carats last year.