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The South African-diamond headquartered mining group Petra Diamonds has announced that it has sold a 425-carat diamond to consortium comprising to Belgian companies, the Stargems Group and Choron (Belgium) BVBA, for $15 million.

It was the largest of four massively valuable stones discovered this year at the company’s Cullinan Mine, which is located several kilometers northeast of the South African capital city of Pretoria. During the course of March and April, the mine also offered up a 209.9-carat, D color, Type II gem-quality diamond; a 100.83 carat gem-quality diamond; and a 6.12carat Type II fancy color blue stone.

Where just one of those stones would qualify as the best ever produced at a range of diamonds around the world, for Cullinan it is pretty much just another day at the office. Nonetheless, these latest finds came at a good time, for they will provide much needed cash to bring down a debt burden that Petra has accrued in expanding mining operations at the site.


Originally known as the Premier Mine, the name Cullinan comes from the township 38 kilometers northeast of Pretoria. Early reports of diamond discoveries in this area dates back to 1871, when a 4.250-carat stone carat was found on a nearby farm, and other gems were also found on the banks of the Elands River, which flows through the region.

The Premier Mine was originally part of farm property sold to British prospector, Sir Thomas Cullinan, after the Anglo Boer War at the turn of the 20th Century for £52,000.

The diamondiferous ground at Cullinan was found to comprise a huge volcanic kimberlite pipe, which spread over the surface for at least 80 acres. Production at the Premier Mine began on April 24, 1903 and by 1904 the mine comprised three open-cut pits employing more than 2,000 people. 


A 424.89 carat rough diamond and a 209.2 carat rough diamons recovered at Cullinan in March and April of 2019. Both are traded as D-color stones.

On January 5, 1905, a diamond of 3,253.75 carats in its uncut state was found in the side wall of the open workings of the No. 2 Mine by the mine manager, Mr. Frederick Wells. The news was transmitted by telegraph and cable around the world that the world’s greatest diamond had been discovered. 

The giant rough diamond, by far the largest rough stone ever recovered, was named “The Cullinan Diamond.” It was presented to England’s King Edward VII in recognition of his granting a constitution to the Transvaal Colony in South Africa. 

The two principle stones were subsequently cut from the Cullinan Diamond, and both now are in the British Crown Jewels. The larger of the two is the “Star of Africa” (530 carats), which is set in the Royal Scepter, and other is the “Lesser Star of Africa” (317 carats), which was set in the Imperial State Crown.


In 1917, after a hiatus in mining caused partly by the 1st World War, the Premier Mine De Beers Consolidated Mines acquired a controlling interest in the mine and production resumed at the mine. De Beers would control the property for the next 90 years, when it was acquired by Petra. The new owners changed the name of the facility to the Cullinan Mine.

Among the notable rough diamonds that recovered from Premier Mine was the Premier Rose (353 carats), the Niarchos (426 carats), the De Beers Centenary (275 carats), the Golden Jubilee Diamond (755 carats) and the Taylor-Burton Diamond (69 carats).

Among the diamonds discovered after Petra’s purchase of the facility include the Cullinan Heritage (507 carats), which sold in February 2010 for $ 35.3 million. To date it is the highest price on record ever paid for a rough diamond.

An early morning view of the Cullinan mine in South Africa.