Diamond Knife Sharpener 23-cm | 9-inchA sharpening rod with a diamond coating, which should be used for dull or moderately sharp knives. The special shape of the diamond grit on the sharpening rod ensures exceptional sharpening of the knife blade. The result: a smooth, sharp edge. Diamond sharpening rods are available in fine and normal grit. As these rods remove a tiny amount of metal from the knife, we recommend an additional WSTHOF Honing Steel for daily or weekly sharpening.