Petra Diamonds recovers 121.26 carat white diamond at Cullinan mine

The company said the stone is a Type II diamond of “exceptional colour and clarity, and is an outstanding example of the large, high quality diamonds for which the mine is known”.

It will be sold in the last tender of Petra's 2016 financial year, which is currently underway in Johannesburg.

“This, along with a number of other high quality stones that will also be included in the tender, will deliver an improved product mix at the mine in the last quarter of FY 2016.”

RBC Capital Markets said that based on prices received for what appear to be similar quality stones by other mines, Petra should achieve at least $3.5m for this diamond.

Analyst Des Kilalea said: “While the proceeds are small in relation to the market cap and thus should have only limited impact on our valuation and the share price today, the recovery is positive in that it could be one of the first points in a trend of better stones coming from new undiluted ore in the developing block cave at Cullinan.

“In addition, this is a small positive for the balance sheet which is approaching peak net debt.”