The Cullinan kimberlite pipe was discovered in 1902 and open pit mining commenced at the ‘Premier’ mine (as it was then known) in 1903. Ore extraction has been by underground mining methods since 1946. Ore extraction has varied between 2 and 5 Mt per annum and ore treatment between 2 and 7 Mt per annum.
The mine was renamed ‘Cullinan’ as part of its centenary celebrations and to link the mine to the illustrious heritage of the Cullinan diamond, which provided the two main polished diamonds within the British Crown Jewels (the 530 carat Great Star of Africa and the 317 carat Lesser Star of Africa).
Petra Diamonds initially acquired a 37% interest in the Cullinan mine from De Beers in 2008, but increased its direct interest in the mine to 74% in late 2009 when it acquired Al Rajhi’s holding in the mine. Petra Diamonds continues to mine the underground resource using block cave mining methods.
Cullinan is renowned as a source of large diamonds and frequently yields diamonds larger than 10 carats. Furthermore, it has produced over 750 stones weighing more than 100 carats, 130 stones weighing more than 200 carats, and around a quarter of all diamonds weighing more than 400 carats.
Cullinan is also renowned as the world’s most important source of blue diamonds, providing the collection of 11 rare blues displayed in 2000 at London’s Millennium Dome alongside the Millennium Star and which included the fancy vivid blue ‘Heart of Eternity’ (27 carats polished).
Since Petra Diamonds took operations over in 2008, Cullinan has produced the following important diamonds:
A 39.9 carat diamond which sold for US$8.8 million in 2008.
A 26.6 carat diamond which yielded a fancy vivid blue and internally flawless 7.0 carat polished stone known as the ‘Star of Josephine’ and sold for US$9.49 million at a Sotheby’s auction in 2009.
A 507.5 carat white diamond known as the ‘Cullinan Heritage’ which was sold in 2010 for US$35.3 million.
A 25.5 carat blue diamond which sold for US$16.9 million in 2013.
A 29.6 carat blue diamond which sold for US$25.6 million in February 2014 and was then cut and polished into the perfect 12 carat ‘Blue Moon’.
A 122.52 carat blue diamond which achieved a value of US$27.6 million in 2014.
A 232 carat white diamond which was sold for US$15.2 million in September 2014.
Other notable diamonds historically produced from Cullinan include the Premier Rose (353 carats rough), the Niarchos (426 carats rough), the De Beers Centenary (599 carats rough), the Golden Jubilee (755 carats rough) and the famous Taylor-Burton diamond (69 carats polished).
The Cullinan Diamond as found, broken down and cut as crown jewels