PURPOSE: To minimize the heating value in cutting, double the cutting speed and substantially enhance the durability of a diamond cutter for casting by making diamond abrasive grains exist on both peripheral edge face and side faces of a metallic wheel disk.

CONSTITUTION: On the peripheral edge face of a type metallic wheel disk 2' of 1.0-2.0 mm in thickness and the entire surface or part of each side of the disk 2' are diamond or borason abrasive grains 5 of 20 through 50 meshes in grain size and diamond, borason, alumina or zirconia abrasive grains of 30 meshes or less in grain size made to exist embedded in the layer of nickel or cobalt plating by way of electroplating, respectively. As a result when a diamond cutter is tilted to bring into contact with a casting workpiece, the existing of these abrasive grains 5 prevents the metallic disk 2' from the direct contact with the casting workpiece for reducing the heating value, vibration and so on in cutting. This leads to doubling of the cutting speed and also substantial increase in the durability of the cutter.