RAPAPORT... Rio Tinto's rough-diamond production from its Diavik mine in Canada rose in the first quarter amid the recovery of higher-grade ore.Output climbed 18% year on year to 1 million carats for the three months ending March 31, the company said Tuesday. The miner saw improvements to the productivity of its processing plant, as well as greater ore availability and higher grades.The company expects total diamond recoveries for the year to come to between 3 million and 3.8 million carats. This year is the first to exclude output from the miner's Argyle site in Australia, which closed in November. Full production for 2020 came to 14.7 million carats. However, output for Diavik alone was 3.7 million carats last year, Rio Tinto noted.Rio Tinto owns a 60% stake in Diavik, with Dominion Diamond Mines holding the remainder.Image: Rough diamonds from the Diavik mine. (The Diavik Diamond Mine)