RAPAPORT... Rio Tinto expects diamond production of between 17 million and 20 million carats in 2018, representing a decrease in output compared to last year. The company did not explain the expected drop.Diamond production in 2017 grew 21% to 21.6 million carats, driven by a 23% jump in output at its Argyle mine in Australia. The company also owns a 60% stake in the Diavik mine in Canada, where production rose 12% during the year, Rio Tinto reported last week. During the fourth quarter, Argyle production jumped 71% year on year to 6.1 million carats, due to additional processing of higher-grade alluvial tailings. Diavik yielded 1.1 million caratsfor the quarter, a 7% year-on-year rise, driven by improved recovery grades. Image: Rio Tinto