JOHANNESBURG (miningweekly.com) – The illustrious Cullinan diamond mine, flagship of London-listed Petra Diamonds, is not only famous for hosting the largest gem diamond but a flurry of reports is now affording sky-high status to the latest big blue diamond find at the mine.

Located about 100 km north-east of Johannesburg 25 km from Pretoria, Cullinan is owned by the London Stock Exchange-listed Petra Diamonds.

“The latest blue diamond recovered at the famous Cullinan diamond mine, discovered in 1902, is another rare and exceptional Type-2b stone,” diamond mining luminary Dr John Bristow pointed out in response to Mining Weekly’s request for insight.

“The mine is famous for these stones and rare large Type-2a white stones, as for example the 3 106 ct Cullinan diamond found in 1903.

“This latest exceptional blue diamond will hopefully achieve a top dollar price for Petra, who like all kimberlite diamond producers have been under considerable financial stress given depressed natural diamond prices over the past three years.

“This latest stone could potentially provide much needed uplift for Petra’s balance sheet if the dollar per carat value realised is in line with previous blue diamonds mined and sold from Cullinan,” added Bristow, who is himself renowned for developing a unique micromineral (perovskite) age-dating technique at the Research School of Earth Sciences (RSES), Australian National University, Canberra, with Hugh Allsopp (Bernard Price Institute, University of the Witwatersrand) and Bill Compston (RSES) in the 1980s, courtesy of De Beers.

Forbes reported on January 16 that experts believe that Cullinan's latest 41.82 ct blue diamond could be one of the most significant ever recovered.

Highlighted by Rapaport on January 14 was the big blue diamond's significance for Petra, which has been facing challenges owing to lower demand for diamonds in the past few years. The average October price Petra received for rough, Rapaport pointed out, fell 13% to $110/ct in the first fiscal quarter that ended September 30, amid the company having drawn its $102-million revolving credit facility as of September 30.

The Diamond Fields Advertiser estimated in a separate report that the big blue diamond could fetch R655-million once polished and Instagram quoted Johannesburg’s third-generation diamond dealer and manufacturer of important fancy coloured diamonds Gregory Katz as saying that the discovery could be exceptional if early reports prove accurate.

“As remarkable as the diamond itself may be, its impact extends far beyond the global luxury market, Only Natural Diamonds Jewelry & Watch editor Grant Mobley explained in a widely circulated January 14 newsletter.

“On average, around 80% of the value generated by responsibly recovered diamonds remains within the local economies. That revenue will support jobs, infrastructure, education, healthcare, and essential social programmes.

“At Cullinan, responsible production is at the centre of their operations. Petra reports that 100% of procurement spend at its South African operations goes to local suppliers, further supporting the economy. Petra also prioritises training, education, and skills development for people in the community, enabling long-term economic impact and job creation,” added Mobley.

In a media release, Petra described the big blue diamond as seemingly being of exceptional quality in terms of both its colour and clarity and that the company was ascertaining the preferred sales method.

On the general diamond front, meanwhile, the first of De Beers' ten 2026 sales schedules is under way, with nine more to follow.

Against the backdrop of ongoing diamond industry uncertainty, Rapaport's website states that the De Beers sales will take place in South Africa, Botswana and Namibia and that the April and September sights will be over four days rather than the traditional five days.