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Reserves & Resources

We manage a world-class resource of ca. 250 million carats

Petra Diamonds Limited (“Petra” or the “Company” or the “Group”) manages one of the world’s largest diamond Resources of ca. 250 million carats (“Mcts”). This major Resource implies that the potential mine lives of Petra’s core assets could be considerably longer than the current mine plans in place at each operation, or could support higher production rates.

Gross Resources

As at 30 June 2019 the Group’s gross Diamond Resources (inclusive of Reserves) decreased 15% to 248.15 Mcts (30 June 2018: 290.48 Mcts), predominantly due to a new resource estimate for Cullinan, but also for Finsch and Williamson as well as depletion by mining activity at all operations, and the disposal of Petra’s interest in Helam. An interim Resource estimate for Cullinan has been completed, and will be updated once the C-Cut bulk sampling programme is completed in December 2019.

Cullinan’s gross Resource decreased 19% to 154.9 Mcts (FY 2018: 190.3 Mcts), in line with an interim Resource estimate carried out by Z-Star Mineral Resource Consultants (Pty) Ltd on the Cullinan kimberlite pipe. This was based upon a new geological model, incorporating data from C-Cut Phase 1 development tunnels, as well as additional micro-diamond sampling data and new diamond grade information from the C-Cut bulk sampling programme. However, there has been no material impact on the Cullinan Reserve for mine planning purposes as the effect of the revised Resource estimate was taken into account as part of the plant recovery factors calculated for the new Cullinan plant on the previous Resource estimate.

Gross Reserves

The Group’s gross Diamond Reserves decreased 0.9% to 42.51 Mcts (30 June 2018: 42.92 Mcts) due to depletions, changes to block cave and sub-level cave designs at Finsch, and a Reserve of 60.5 Mt and 4.30 Mcts being declared at Williamson.


Summary of Gross Reserves and Resources

The following table summarises the gross Reserves and Resources status of the combined Petra Group operations as at 30 June 2019.

Category Tonnes (millions) Grade (cpht) Contained Diamonds (Mcts)
Probable 146.6 29.0 42.51
Sub-total 146.6 29.0 42.51
Indicated 376.8 45.1 170.06
Inferred 1,298.4 6.0 78.10
Sub-total 1,675.2 14.8 248.15


Download the Company’s 2019 Resource Statement

Key Facts

  • ca. 250 Mcts Resource: largest outside the majors
  • 42.51 Mcts Reserves