PURPOSE: To easily and accurately perform visual recognition and discrimination of a cutting part tip form so as to enhance efficiency of analyzing operation and improve reliability by selectively applying a masking process to a binder (bond) holding diamond abrasive grains.

CONSTITUTION: A masking layer of clear and uniform color tone which can be discriminated from diamond abrasive grains is applied to a surface part of bond. First, water washing is applied after degreasing cleaning with a volatile solvent, and then acid cleaning is applied with an aciditic aqueous solution so as to remove an oxide film on the surface. Out of electroplating, electroless plating, electrostatic coating and the like listed as a masking process method, the electroplating utilizing an electric specific resistance difference between diamond and bond is preferable. In this case, electrolytic copper plating using copper cyanide. copper sulfate or the like is preferable, and in these, copper cyanide plating can provide a clear and uniform masking and easy operability. As a result of this masking process, discrimination between the diamond abrasive grains and the bond is clarified and analysis through visual observation can be facilitated.