diamond's natural hardness

The hardest natural diamonds in the world are from the Copeton and Bingara fields located in the New England area in New South Wales, Australia. They were called can-ni-faire ("cannot be processed"—a combination of English "can", Italian "ni" = not and French "faire" = do^[14]) by the cutters in Antwerp when they started to arrive in quantity from Australia in the 1870s. These diamonds are generally small, perfect to semiperfect octahedra, and are used to polish other diamonds.