Abstract: A method of machining a diamond workpiece by a laser beam in which a metallic membrane or layer is formed on at least one surface of the workpiece before the workpiece is subjected to the machining operation. The metallic membrane or layer is preferably formed on both side surfaces of a plate-like diamond workpiece. The workpiece machined according to the present invention has a good appearance without cracks and splinters, and a smooth cut surface.

Abstract: A grinding wheel comprising abrasive grains each of which is coated with a conductive material and a non-conductive binder interposed among said abrasive grains. The amount of said conductive material ranges from 30 to 80% by weight based on said abrasive grains. The abrasive grains coated with said conductive material is contained in said grindstone in an amount ranging from 33 to 64% by volume. A method of producing said grinding wheel is also proposed. The method comprises preparing a mixture of said coated abrasive grains and said non-conductive binder, filling the mixture into a mold and molding said mixture by applying a pressure while maintaining said mixture at a constant temperature.