Petra Diamonds has sold its cutting and polishing business Calibrated to Gem Diamonds. Petra Diamonds said it sold the division to focus on its core aspects of production and exploration.

Calibrated was sold for a consideration of R47m (£3m). The deal with Gem Diamonds allows Petra Diamonds to have access to the facilities for the next 30 months.

Petra Diamonds bought Calibrated for R47m (£3m) in November 2006 with the objective of boosting its revenues by polishing and cutting its own rough diamonds. The diamond mining side of the business has accelerated significantly over the past year making the extra revenue from Calibrated a less important part of the business.

Petra Diamonds chairman Adonis Pouroulis said: “Since the acquisition of Calibrated, Petra has transformed its diamond production operations with the acquisitions of the Cullinan, Koffiefontein, Kimberley Underground and Williamson diamond mines, with a corresponding increase in group production. Petra is expecting substantial revenue and cash flow from these assets and the increased focus will enable the company to maximise returns."

Petra Diamonds expects to produce more than 1m carats in the next financial year. Last year, the diamond group produced 200,000 carats.

Earlier this month Petra Diamonds sold a 39.19ct blue diamond for $8.8m (£5.5m).