Rio Tinto and diamonds

Rio Tinto is a world leader in finding, mining and processing mineral resources. The Group's worldwide operations supply essential minerals and metals that help to meet global needs and contribute to improved living standards worldwide.

Diamonds are an integral product group for Rio Tinto. Rio Tinto's Diamonds business unit continues to expend a significant proportion of its exploration budget in the search for world class diamond deposits and to grow its substantial investment in the diamond industry.

The story of Rio Tinto Diamonds begins in 1972 with the discovery of diamonds in the east Kimberley region of Western Australia, when Ashton Mining Limited, an Australian company, explored for diamonds in the Kimberley region of Western Australia, under the Kalumburu Joint Venture. Over the next few years small diamond and alluvial deposits were discovered.

In 1976, CRA Ltd (later to become Rio Tinto Limited) took over management of the group, which became known as the Ashton Joint Venture. CRA introduced a number of specific exploration objectives, including finding a diamond that was larger than a quarter of a carat, discovering a diamond-bearing pipe and finally locating a diamond-bearing pipe with a diamond grade high enough to justify a mine.

From 1977 to 1979, increasingly large deposits of diamonds were discovered, including the main Argyle mine pipe known as the AK1 Pipe. In 1983, Rio Tinto established a mine and the Argyle Diamond Mines Joint Venture and the Argyle Exploration Joint Venture were formed to replace the Ashton Joint Venture. Alluvial mining commenced at Smoke Creek in 1983 and the construction of the nearby Argyle mine began in 1984. The Argyle Diamond Mine was commissioned in December 1985.

Rio Tinto's diamonds operations have since evolved to encompass the production from diamond mines in Canada, Australia and Zimbabwe, sorting and valuation activities in Antwerp, cutting and polishing in Perth and market support activities in India and the United States.

Through our 100 per cent ownership of the Argyle Mine, 60 per cent ownership of the Diavik Diamond Mine in Canada and 78 per cent share of the Murowa Mine in Zimbabwe, Rio Tinto produces around 20 per cent of the world's diamonds by volume.