Chef's Garage 3 Stage Kitchen Knife Sharpener, Sharpens Your Dull Straight and Ceramic Knifes Quick and Easily (Black) The first section is diamond coarse slot which sharpens and straightens the damaged blades. The second slot restores its V-shape and the third slot polishes to provide a fine finish. With our chef's garage knife sharpeners, chopping and slicing becomes a less troublesome task. If you want to save up time and chop the vegetables as smooth as butter then you surely need a great knife sharpener. This sharpener is perfect for sharpening the metal blades but it is not suitable for serrated and ceramic blades