The move from open pit mining to an underground operation will extend the life of Argyle until at least 2020.
The US$2.2 billion underground mine uses the latest in block caving technology and is the first of its kind in Western Australia.
The average annual production over the life of the underground mine is likely to be 20 million carats per year.
Western Australia’s Minister for Mines and Petroleum Bill Marmion attended the commissioning ceremony and was joined by Traditional Owners, government representatives, Rio Tinto executives and employees.
Rio Tinto diamonds and minerals chief executive Alan Davies said the Argyle mine had produced some of the world’s most spectacular diamonds and had delivered many benefits to the local region.
“The new Argyle underground mine has allowed us to extend the life of this iconic asset for Rio Tinto and Western Australia. I am proud that we can continue our contribution to local employment and the economic development of the East Kimberley region, as we have over the past quarter of a century.”
With 70 per cent of the workforce living locally, Argyle is one of the largest contributors to the East Kimberley economy. Indigenous Australians account for one in four members of the local workforce.
The Argyle mine has produced some 800 million carats of rough diamonds over the last 25 years including a small but consistent supply of the world’s rarest pink diamonds.
Argyle diamonds are highly sought after for fashion jewellery in both established and emerging markets.
Argyle Diamond Mine managing director Kim Truter said “The Argyle Diamond Mine is a world class resource which has been strongly supported by Rio Tinto since exploration began in the 1970s.
“A new chapter begins at Argyle and I am proud to acknowledge the many men and women who have contributed to the discovery and development of the mine and the production of some of the best diamonds the world as ever seen,” he said.