Rio Tinto has announced a $40 million investment in the first phase of underground mining below the A21 open pit at the Diavik Diamond Mine in Canada's Northwest Territories. The updated mine plan and production schedule for the mine includes the A154N and A154S pipes, and upon approval of the second phase of the A21 underground project, the Diavik mine is expected to end commercial production in Q1 of 2026. The first phase of underground mining of the A21 pipe is predicted to produce an additional 1.4 million carats of rough diamonds, with current employees and contractors being transferred from other areas of the mine.

Rio Tinto Minerals' Chief Executive, Sinead Kaufman, explained that the decision to invest in the underground development of the A21 pipe was based on the compelling industry fundamentals, the company's experience in safely developing diamond mines in extreme conditions, and its track record of success in the global diamond industry. The company anticipates seeking approval for Phase 2 of the A21 underground project in H1 2024, which is expected to yield a further 0.8 million carats of rough diamonds.

Diavik, which is fully owned and operated by Rio Tinto, is the largest diamond mine in Canada in terms of production. It produces 6-7 million carats of rough diamonds each year, and since the commencement of mining in 2003, over 100 million carats of diamonds have been produced. Construction of the A21 open pit began in 2015 and was completed safely and ahead of schedule, enabling commercial production to begin in 2018.