The ceramic used in watchmaking is not the kind found on tiles: it is almost always zirconium oxide (ZrO₂), sintered at temperatures around 1,400 °C and then worked with diamond abrasives. Hardness reaches 2,300 Vickers compared to approximately 200 for stainless steel. This makes it practically immune to scratches from daily use. The downside is structural: the harder a material is, the more it tends to be brittle. A ceramic case that falls on a hard surface can chip or break cleanly, without the slightest warning sign. Those who work at the bench see it: the watch arrives perfect except for a broken corner.
The production process is the real bottleneck. During sintering the piece undergoes shrinkage of up to 25% compared to the initial dimensions of the green ceramic. Compensating for this shrinkage with the precision that watchmaking requires is difficult, and explains why very few manufacturers can make entire ceramic cases without resorting to specialized suppliers. Brushed finishing is even more complex: it requires dedicated diamond abrasives and long processing times, which is why most ceramic watches leave factories with entirely mirror-polished surfaces.
Colors are a real advantage over coatings. In ceramic pieces the color is incorporated into the mass during manufacturing, by mixing metallic oxides with zirconium powder before sintering. There is no surface layer that can wear away. Rolex exploits this principle in Cerachrom, the ceramic bezel insert used on the Submariner and GMT-Master II: the color does not fade, unlike the previous anodized aluminum insert. Omega with Ceragold combines ceramic and gold for the tachymeter scale of the Speedmaster bezel, guaranteeing durability without sacrificing legibility.
Some companies have developed hybrid variants to correct brittleness. IWC patented Ceratanium, which blends titanium and ceramic, and uses zirconium oxide in the Pellaton winding system components to reduce wear on moving parts. Panerai presented a dense ceramic layer applied over titanium with fracture resistance declared ten times superior to conventional ceramic. Swatch works with a Bioceramic, a ceramic-plastic composite that is lighter and less brittle, but with different physical properties than pure ceramic. IWC also developed Ceralume, which incorporates Super-LumiNova pigments directly into the ceramic mass: currently it is the only homogeneous luminescent ceramic, not an overlaid coating.
From a hypoallergenicity standpoint, zirconium oxide ceramic contains no nickel or free chromium, making it suitable for those with skin reactivity to metals. It is not magnetizable. Its weight is less than steel but greater than pure titanium.