Petra Diamonds reviews Finsch future as smaller rough prices weaken cash flow

Petra Diamonds is weighing the future of Finsch as weaker prices for smaller rough stones squeeze cash generation across its South African business, a sign that the strain in melee and commercial-quality goods is now shaping mine strategy, not just quarterly sales. The company said it had launched an immediate cost- and capital-expenditure reduction assessment to preserve liquidity, including a review of whether to suspend further spending at Finsch while it concentrates on higher-value production at Cullinan.

The pressure showed up clearly in Petra’s Q3 FY 2026 operating update on May 8. Sales rose to US$68 million, helped by the sale of a 41.82-carat Type IIb blue diamond, but pricing remained under pressure, especially in smaller size fractions at both mines. Net debt increased to US$298 million at March 31, 2026, from US$284 million at December 31, 2025, and the revolving credit facility was fully drawn. Petra said it was rephasing operating and capital expenditure, prioritizing mining areas with the best near-term value and cutting non-core spending wherever it can.

Finsch carries real weight in that equation. The mine has been operating since 1967 and Petra describes it as South Africa’s second-largest diamond operation by production. It is also one of the company’s two core underground mines, alongside Cullinan. Petra had previously said Finsch was operating in line with expectations on a two-shift system introduced at the start of FY 2025, but the longer slump in smaller-stone pricing has now pushed the mine back into strategic review. If Petra pauses additional capital there, the question is no longer only how much rough Finsch can produce, but whether the mine can justify further investment while the cash pool narrows.

Cullinan is being pulled in the opposite direction. Petra is focusing on the Eastern areas of the C-Cut ore body, which contain high-value Type II stones, but that shift lowers output because those areas are lower grade than the CC1E block that had underpinned the current plan and guidance. Petra said full-year carat production guidance at Cullinan was unlikely to be met and suspended that guidance for the rest of the year.

The tension is not new. In August 2025, Petra said it had already achieved US$18 million to US$20 million in cost reductions against prior guidance and was trying to preserve cash while completing extension projects at both Cullinan and Finsch. Later in 2025, the National Union of Mineworkers said about 468 workers at the two mines faced retrenchment notices, while Petra secured refinancing that extended a US$99 million revolving credit facility to December 2029 and US$228 million of second-lien notes to March 2030. A rights issue raised about £18.8 million, or US$25.1 million, but the latest review suggests the hard part is now the business of deciding which parts of the portfolio still deserve capital.