(IDEX Online) - Canadian miner Star Diamond claims Rio Tinto, senior partner in a joint exploration project, may be to blame for damage to some sample stones.The two companies are already tangled in a legal row over terms of another venture. Star Diamond accuses Rio Tinto of "bad faith predatory practices", gross overspending on exploration costs at the Star-Orion South project in Saskatchewan, and failing to share results of drill sampling.The new disagreement centers on Star Diamond claim, made in a press release, that "recent diamond breakage has occurred in the diamond parcels recovered ???,? ? suggesting the extraction and/or processing systems being used by Rio Tinto may be resulting in diamond breakage," from 10 trenches at the Project Falcon site (pictured), in the Fort a la Corne forest. It suggests Rio Tinto, the Anglo-Australian mining company, may be responsible.The company added comprehensive studies would be required to deduce if Rio Tinto's methods are damaging potentially larger diamonds.Further work still needs to be done to assess Rio Tinto's extraction and processing systems that have so far recovered 2,500 diamonds weighing about 120 carats, it said.Rio Tinto said it could not comment directly on the claims.