Rio's diamond unit fades to $118 million as Diavik winds down

§1A wind-down with a revenue line.

Rio Tinto's diamond business is now a wind-down with a revenue line. First-half sales fell twenty-seven percent to $118 million, rough-diamond output dropped fifty-one percent to 1.1 million carats, and the unit swung to an underlying EBITDA loss of $72 million from a $55 million loss a year earlier. These are the numbers of a mine being emptied, not run.

Diavik, in Canada's Northwest Territories, closed in March after reaching the end of its ore life, and Rio is processing the last of its stockpiled material through at least the end of 2026. With Argyle shut since 2020, Diavik was the miner's final diamond asset; when the stockpile is gone, one of the world's major producers exits the business entirely.

§2The expensive tail.

The tail is expensive. Rio expects to spend roughly $1 billion over the coming years on closure and rehabilitation across Diavik, Argyle and its other legacy sites — the unglamorous back half of mining that arrives long after the last carat is sold. A diamond unit that once anchored supply from the far north now shows up mainly as a remediation bill.

§3A supply cliff, previewed.

For the wider market the exit tightens an already thinning supply of natural rough at the top and middle. Diavik's better goods fed a specific appetite for Canadian-origin, conflict-free stones, and that provenance does not transfer to another mine. As Diavik and its peers close without like-for-like replacements, the scarcity argument that Gem Diamonds is monetizing at the high end gets structurally stronger.