The hard coated abrasive medium is formed by providing a hollow body with abrasive deposit on the outer surface. The buoyancy is provided by the enclosed air space, and the weight is defined by the weight of the body plus the hard plating or the abrasive grit deposited thereon. The density is selected in accordance to the character of the workpiece with which it is to be used in order to optimize the abrading action by interacting with the workpiece in the optimum fashion. In one embodiment, the abrasive grit is bonded to the exterior surface of the abrasive medium in a spiral shape to accelerate the abrading action.