How Are Diamonds Mined?

We seldom think about how the diamonds we wear came to us. Natural diamonds, as opposed to synthetic diamonds or fake diamonds, are mined from the earth. There are currently two methods of mining diamonds: Pipe Mining and Alluvial Mining.

Pipe Mining
When pipe mining is used, the diamonds are extracted from the earth through volcanic pipes. These are not man-made pipes - they are natural pipes in the ground. Shanks are put into the ground next to the pipes, and tunnels are driven into the deepest parts of the pipe. The diamonds are not sorted out at the mine. Instead, huge rocks that are full of diamonds are brought out of the mine and moved to a screening plant for separation.

Alluvial Mining
The Alluvial mining method is done in riverbeds and on beaches. Walls are built to hold back the water and the sand on the bank or beach. The sand is moved with a bulldozer until the level of earth that diamonds can be found in is reached. Again, the diamonds are not sorted here. Instead, the sand that contains the diamonds is bulldozed into trucks, and taken to screening plants.

At the diamond screening plants, natural rough diamonds are extracted from the rocks and earth, and then undergo cutting and polishing, before finally becoming the diamonds we see on jewellery.

Diamond Mines Around the World

Argye mine located in the Kimberley region in the far north east of Western Australia. Owned by Rio Tinto, this mine is the world’s largest single producer of volume of diamonds. However, due to low proportion of quality diamonds it is not the value leader. It does produce 90-95% of the world’s supply of pink diamonds.

Diavik is also owned by Rio Tinto, located in Canada, it is a very large mine. It is located north of Yellowknife and south of the Artic Circle on an island. The island is connected by an ice road. It is also an important part of the regions economy employing more than 700 people and producing more than 8 million carats annually.

Ekati diamond mine is owned by BHP Billiton and located south of the Artic Circle in the Northwest Territories of Canada. The Ekati is Canada’s first operational diamond mine. Diamonds mined here are sold under the Aurias trade name. Authenticity is verified through CanadaMark service. CanadaMark service is also owned by BHP Billiton Diamonds, Inc.

Baken diamond mine is located along the lower Orange River in South Africa. It is owned and operated by Trans Hex. The average size stone for 2004 was 1.29 carats. In 2004, this mine produced a 78.9 carat D color flawless diamond that sold for more than 1.8 million US dollars, as well as a 27.67 pink diamond that was sold for over 1 million US dollars.

Merlin is the second of only two diamond mines in Australia. It was once owned by Rio Tinto and sold to Striker Resources, and subsequently became North Australian Diamonds.

Orapa is the world’s largest diamond mine. It us located 240 Km west of Francistown. The mine is owned by Debswana, which is a partnership between De Beers and the government of Botswana. This mine operates 7 days a week. It maintains pre-primary and primary schools for its employee’s children. There is also a 100 bed hospital and game park. This mine began production in 1971 and is the oldest mine owned by the Debswana Company.

The Premier mine located in Cullinan, South Africa produced the largest diamond, the Cullinan Diamond, ever in 1905. The rough Cullinan Diamond weighed 3,106.75 carats (no. 17 in photo). The famous Hope Diamond, 44 carats, (no. 11) is small compared to the Cullinan Diamond.

This mine also produced the Golden Jubilee diamond which weighed 545.67 carats. This mine is formally owned by the De Beers Company and was renamed The Cullinan Diamond Mine in 2003 in celebration of its centennial. It was sold to Petra Diamonds in November 2007.

Recently, in September 2009, yet another giant 507 carat white diamond was discovered in the Cullinan mine.