Kasumi Combo Ceramic Whelstone 1500/4000 The main cutting blade of Kasumi knives is made of V Gold No. 10 high carbon stainless steel that has been developed especially for knives. The blades are hardened to Rockwell C59 60 degrees, and, therefore, keep a sharper cutting edge longer than any other knives. On both sides of the main cutting blade, fine damascus stainless steel pattern is clad. The Kasumi pattern that you see on both sides of the knives is the result of the repeated folding and forging of fine stainless steel into multiple layers. Each knife is carefully finished throughout each step of the manufacturing process by the hands of skilled craftsmen. The beauty of the Kasumi pattern together with the strong black laminated wooden handles makes these knives look graceful, yet strong and good for any style of cooking.