A ceramic knife is a knife made out of very hard and tough ceramic, often zirconium dioxide. Ceramic Knife is used for slicing fruits, vegetables and boneless meats. Even so, ceramic knives are intended to complement not replace your other cutlery. Use steel knives for carving, prying, boning, cutting frozen foods. Avoid flexing or prying. Always use them on a plastic or wood cutting board and avoid cutting on marble, stone or inappropriate surfaces like plates or kitchen tile.