A ceramic knife stays sharp for years, but it will eventually need sharpening. Due to the brittle blade, this isn’t always an easy task. Many manufacturers will allow you to send the knife to them for professional sharpening, and it may even be free of charge. Diamond wheel sharpeners can be purchased to sharpen a ceramic knife. However, you must be careful. It’s often better to pay for a professional service, rather than attempting a home sharpening.