TORONTO (miningweekly.com) – South Africa-focused Rockwell Diamonds has found four heavyweight stones, each weighing more than 100 ct, from its Middle Orange River (MOR) alluvial operations during the past three weeks, reinforcing management's decision to focus operations in this region and embrace new processing technology.

The TSX- and JSE-listed miner on Tuesday said it had also recovered a higher-than-average number of diamonds smaller than 100 ct.

Among the heavyweights were two stones weighing 116 ct and 138 ct, which were recovered at the Saxendrift processing plant from gravels originating from the Saxendrift Extension pit. A 126 ct stone and a 169 ct stone were also recovered from a recently opened-up mining area at the Saxendrift Hill Complex (SHC). The freshly commissioned SHC plant uses Bourevestnik X-ray technology in both the concentration and recovery areas.

Rockwell said all these stones would be sold into the beneficiation joint venture with Steinmetz Diamonds at market value, and Rockwell would also participate equally in the value uplift once these stones had been polished and sold.

Rockwell's recovery rate in the 20 ct to 100 ct category had improved after commissioning the SHC and Niewejaarskraal operations, and through integrating the Saxendrift Extension into Saxendrift's mine plan. Implementing diamond value management principles and fit-for-purpose technologies also contributed to the improvement, the company said.

"Recovery of four rough diamonds exceeding 100 ct within a three-week period is a milestone in our objective to grow production in the MOR region where we have a significant inventory of high-value in situ diamonds.

"Our objective to increase alluvial production volumes in this area to 500 000 m³/m is aimed at improving the quarterly earnings visibility of the company through the more regular production of large stones such as these. Importantly, these plus-100 ct stones were recovered from two new mining areas, and show tangible progress with our strategy,” president and CEO James Campbell said.