Rio Tinto is one of the world's leading producers of industrial and gem quality diamonds through its operating and management interest in the Argyle diamond mine in the Kimberley region of Western Australia. Production started in 1985 where a conventional open pit mine based on the AK1 kimberlite pipe is supported by a smaller alluvial operation. The entire diamond recovery operation is controlled by state-of-the-art computer technology. In particular, ingenious x-ray technology identifies the diamonds and removes them from the concentrated ore. Argyle markets all its gem and industrial quality diamonds independently through its own sales office in Antwerp, Belgium. Some of the mine's famous pink diamonds are sold by an international tender process. A portion of its rough gem diamonds are further processed in Australia and elsewhere prior to final sale. Development studies have added enough ore to extend the mine life into 2006 at current mining and processing rates, with further potential thereafter. Argyle employs approximately 725 people.