A processing method includes: a step of setting a workpiece having a workpiece surface made of a material containing metal, on a precision processing machine; and a forming step of forming multiple grooves having a V-shaped cross-section, at intervals of a constant pitch in a predetermined area on the workpiece surface, using a tool provided in the precision processing machine to thereby form a V-groove pattern made up of the multiple grooves, in the predetermined area. In the forming step, each time one groove is formed, the relative position between the tool and the workpiece is moved in a direction intersecting the longitudinal direction of the groove and the angle of the groove face of the groove is gradually varied so that a uniform color can be visually recognized in every location in the predetermined area when the predetermined area is observed from a predetermined viewpoint.