Abstract: A superabrasive tool such as a superabrasive grindstone (101; 102), a superabrasive dresser (103; 104; 105) or a superabrasive lap surface plate (106) includes a base (20) of steel and a superabrasive layer (10) formed on the base (20). The superabrasive layer (10) includes superabrasive grains (11) consisting of diamond grains, cubic boron nitride grains or the like and a holding layer consisting of a nickel plating layer (16) and a bond layer (17), or a brazing filler metal layer (18), holding the superabrasive grains (11) and fixing the same onto the base (20). Grooves (12) or holes (14) are formed on flat surfaces (19) of the superabrasive grains (11) exposed from the holding layer (16, 17; 18). The holding layer (16, 17; 18) holding and fixing the superabrasive grains (11) so that the surfaces of the grains are partially exposed is formed on the base (20).

Abstract: A blade comprises a disc-shaped substrate having a major surface and an outer peripheral edge portion encircling the major surface, and an abrasive grain layer mounted on the outer peripheral edge portion of the substrate. The substrate includes a first disc having a major surface, and a second disc having a major surface which is superposed on that of the first disc. The major surface of the second disc is separated from that of the first disc, thereby defining a clearance between the major surfaces of the first and second discs and correspondingly forming a convex surface region on the outside surface of the substrate. The peripheral portion of the convex surface region is provided with a contact portion where the major surfaces of the first and second discs are slidably in contact with each other.