Rio Tinto Diamond Exit: Supply Void Sets Stage for Market Rerating as Strategic Review Looms

The final production day at Diavik has arrived. After 23 years of operation, the mine will officially cease active mining on March 24, 2026. Over that period, it produced more than 150 million carats of rough diamonds, a legacy that now concludes. The closure is not a surprise, but its timing is precise: the mine's only remaining resource, the A21 underground section, is due to be depleted at the end of the first quarter of 2026. This marks the definitive end of a major supply source.

The financial context reveals a business under pressure. Despite a 19% revenue increase to $332 million in 2025, Rio Tinto's diamond unit posted an underlying EBITDA loss of $79 million for the year. This loss, though narrowing from the prior year, underscores the operational and market challenges that made the mine's exit a strategic decision. The production surge in 2025, which saw output grow 61% to 4.4 million carats, was driven by a shift to the A21 underground section. That ramp-up was a final push to extract value before the resource was exhausted.

The scale of this closure is significant. Diavik was one of Canada's chief diamond operations, and its departure removes a steady, high-volume producer from the market. The supply void is now a concrete reality, not a future possibility. The key question for the market is how this specific volume-over 150 million carats over two decades, with the final 4.4 million carats representing a concentrated output-will be absorbed. The mine's profitability struggles add another layer, suggesting the exit was driven by economics as much as by resource depletion. This definitive disruption sets the stage for recalibrating supply-demand balances in the years ahead.

The Strategic Review: A Market in Transition

Rio Tinto's decision to consider exiting the diamond business is a direct response to a fundamental mismatch. The company announced a strategic review last week, stating it is exploring a range of options for potential divestment of its diamond interests. The core reason cited is a lack of scale. As CEO Harry Kenyon-Slaney noted, the diamond business does not align with Rio Tinto's strategy of focusing on large, long-life, expandable assets. This move follows a similar path taken by rival BHP, highlighting a broader industry trend of re-evaluating diamond holdings.

This strategic pause occurs against a backdrop of a positive long-term market outlook. The global diamond market is projected to grow from $41.49 billion in 2025 to $54.67 billion by 2033, a steady expansion driven by luxury demand. Rio Tinto itself acknowledges this favorable trajectory, pointing to strongly growing demand and a supply side constrained by a lack of new discoveries. In other words, the market is expanding, but the industry's ability to add new, large-scale supply is lagging.

The tension here is clear. A company with a valuable, high-quality portfolio of mines-Argyle, Diavik, Murowa, and the Bunder project-is stepping back because its diamond assets, while profitable, are simply not large enough to be a strategic priority. The market's growth story is intact, but Rio Tinto sees a better path to value creation elsewhere. This creates a period of uncertainty for the sector. The company has assured stakeholders that operations will continue as usual during the review, but the very fact of a strategic review signals a potential shift in ownership and investment focus for these assets. The market's long-term health is not in question, but the immediate question is who will step in to fill the gap left by a major player like Rio Tinto, and at what scale.

Commodity Balance Catalysts and Watchpoints

The closure of Diavik is a definitive event, but its full impact on the diamond market will play out over time. Several specific catalysts and data points will signal how the supply disruption is being managed and whether the void is temporary or permanent.

First, the financial commitment to closure itself is a key watchpoint. Rio Tinto expects to spend approximately $1 billion this year on closure activities for Diavik and other projects. This significant outlay, while a one-time cost, reflects the scale of the reclamation effort. Monitoring the pace and cost of these activities will provide insight into the mine's legacy and the company's final obligations, but more importantly, it marks the end of any future capital investment in the asset.

Second, the timeline for the final rough diamonds is critical. The mine's last production phase will be polished and sold through 2026 and beyond. This means the concentrated supply from the final 4.4 million carats will not flood the market immediately. Instead, it will be released gradually via Rio Tinto's global network. This staggered sales process is a major factor in delaying the full market impact of the closure, potentially softening any immediate price shock.

Finally, the social and political framework for closure provides another layer of stability. The signing of a Closure Agreement with the Tłı̨chǫ Government in February 2026 formalizes commitments on employment, training, business opportunities, and community funding. This partnership ensures a structured transition for the local economy and reduces the risk of operational or reputational disruptions during the closure phase. It signals a responsible end to the mine's operations, which is important for maintaining the region's stability.

Together, these watchpoints-closure spending, staggered sales, and a formal partnership agreement-will determine the market's adjustment path. If the supply from the final phase is absorbed smoothly and the social transition proceeds as planned, the market may find a new equilibrium. Any deviation, such as a faster-than-expected release of rough or a breakdown in community commitments, could introduce volatility. For now, the catalysts point to a managed exit, but the market's balance will be tested by how these specific events unfold.