Johannesburg: Petra Diamonds said output jumped in the first fiscal quarter as mining grades were higher.

Rough diamond production grew 30 percent to 1.1 million carats in the three months that ended September 30 because of increased contribution from “undiluted run-of-mine ore.” Diamond recovery levels were also lifted by the joint acquisition of the Kimberley mines in January and the subsequent formation of the Kimberley Ekapa Mining joint venture which was effective July 1.

Separately, Petra said four employees were killed in three separate incidents at its mines during the quarter, prompting the company to increase safety initiatives.

At the Williamson mine in Tanzania, a worker was electrocuted, while two employees died in an unrelated accident involving a crane. In addition, a boiler attendant was killed in a shaft accident at the Cullinan mine in South Africa.

“We have embarked upon renewed safety drives to reiterate our zero-tolerance approach to unsafe acts and working conditions with an aim of zero harm to our workforce and contractors,” Johan Dippenaar, Petra’s chief executive officer, said.