Petra Diamonds (LON:PDL) reported an impressive boost to third-quarter revenue on Monday, after production spiked in the first three months of the year.

Revenue for the period rose by 44 percent after the produced and sold more precious stones. The key figure hit $172 million, after selling 1,373,771 carats.

Production too witnessed a rise, up 20 percent to a record quarterly volume of 1,194,947 carats.

“Petra has recorded strong results in both production and sales, as well as a continued improvement in our safety performance,” chief executive Johan Dippenaar said.

“It is also important to note that the make-up of our production is transforming, with higher-value run-of-mine production representing around 82 percent of our carat volume. The future focus of the company will move away from volume targets to value optimisation.”

“While we are very encouraged by the operational delivery against our long-term expansion plans, risks to performance continue to relate to increased volatility in the ZAR/US$ exchange rate, grade and pricing variability at Cullinan, as well as the outlook for Williamson and the blocked diamond parcel.”

The announcement comes just two weeks after the London-based miner announced the finalisation of an agreement with its lenders for a waiver of its December 2017 debt covenant and a resetting of debt agreements for this year.

“The finalization of this agreement with our Lender Group validates its support of Petra’s business and strategy, as we negotiate this final stretch of our expansion programs,” Dippenaar said in the statement at the time.