Johannesburg: Petra Diamonds recovered a 138.57-carat, D-color, type IIa rough diamond, the latest in a string of large stones found at its Cullinan mine in South Africa. The company said it will offer the diamond at its sale in Johannesburg toward the end of the month.

The Cullinan mine is no stranger to large diamonds with recent finds including a 121.16-carat diamond that sold in July for $6 million, or $49,480 per carat. A 122.52-carat, blue diamond was sold in 2014 for $23.5 million, or $971,878 per carat, to a cutting and polishing partnership which cut it into four polished stones. The largest of those, the Cullinan Dream, was sold by Christie’s in June for $25.4 million, or $1 million per carat.

Petra shares rose 2 percent on the London Stock Exchange by midday following the company’s announcement.