Called as A21, the kimberlite pipe will take four years to complete and will require investment of $350m. It is located south of Diavik’s existing mining operations.
The project will require rockfill dike construction to surround the ore body.
Rio Tinto diamonds and minerals chief executive Alan Davies said: "Our decision to invest in the Diavik A21 project reflects our strong confidence in the diamond sector and in our ability to compete effectively in the industry."
The 2015 programme of work has been approved by the Diavik Joint Venture and production from the kimberlite pipe is planned to commence in late 2018.
Rio Tinto holds 60% stake in the Diavik Joint Venture, while Dominion Diamond has the remaining 40% interest.
The Diavik Diamond mine started production in 2003, and became an underground mining operation in 2012.
Image: A rough diamond from the Diavik mine. Photo: courtesy of © 2014 Rio Tinto.
