Decision comes after the companies received Wednesday a preliminary geological assessment of the property, which shows Heritage contains several targets for modern alluvial diamond placer deposits.
Researchers from Curtin University discovered reidite, one of the rarest minerals on Earth buried deep within an ancient meteorite crater in Western Australia.
Efforts to broaden the scope of the Kimberley Process, set to prevent the sale of so-called "blood diamonds", have been stymied for a decade by member states including China, Russia and a number of African nations.