Ceramic knives are made of an advanced, high-tech ceramic called zirconia. This material, which is second in hardness only to diamond, was originally developed for industrial applications where metal components failed. Zirconium oxide is extremely hard, wear resistant, rust-proof, and chemically inert. Their chemical inertness to both acids and alkalis and their ability to retain a cutting edge far longer than forged metal knives makes them a very good culinary tool for slicing and cutting through boneless meat, vegetables and fruits.