RAPAPORT... Rio Tinto has lowered its output forecast for the full year following challenges arising from Covid-19.The miner now expects production from the Diavik mine in Canada to be between 4.5 million and 5 million carats, it said last week. That compares with the 5 million to 6 million carats it predicted at the beginning of the year.Diamond production climbed 35% year on year to 1.1 million carats in the second quarter, as the company's increased its share of rough from Diavik after taking full ownership of the deposit. During the same period last year, Rio Tinto owned 60% of the mine, with Dominion Diamond Mines holding the remainder. "At Diavik, our share of carats were...higher than the second quarter of 2021 due to the benefit of our increased share of production since taking 100% ownership of Diavik from November 2021," the company said. That was "partially offset by maintenance-deficit buildup following Covid-19 disruptions. The maintenance deficit buildup and first-quarter impacts of Covid-19 [have] impacted performance in the first half."During the first six months of the year, production rose 15% to 2.1 million carats.Diavik is Rio Tinto's sole diamond mine following the closure of Australia's Argyle mine in November 2020. Last month, the company put its Star-Orion South exploration project on hold through the end of the year while it weighed a possible exit from the joint venture.Image: The Diavik mine. (Diavik Diamond Mines)