It’s a frequent complaint made by first-time luxury watch owners. Why is it that the stainless steel watch they’ve just spent thousands of dollars on scratches so easily?
The answer is that most brands still use 316L stainless steel, which may only have a hardness of around 220 Vickers. That means you can’t bite into it, but knock it into stone, rock or another metal, and there’s every likelihood you’ll ding your precious new possession. Gold, of course, is far softer still.
Switzerland’s finest watch companies have invested millions into finding more suitable materials to extend the life of their watches. Material gains help explain in part why watch prices have gone up so much in recent times. Materials such as titanium are far more prevalent than they were, while some brands have managed to make cases out of sapphire crystal, one of the hardest materials known to man.
But the most commonly used advanced material in watchmaking is ceramic. Ceramic has many advantages over other materials. It’s hypoallergenic, biocompatible, almost completely scratch-resistant, adjusts quickly to skin temperature and loses little of its new quality over time. Not that it means much in watchmaking, but it’s also highly heat-resistant, so much so NASA used it to cover the now retired Space Shuttle to cope with the high temperatures experienced on re-entry.
The disadvantage of ceramic is that it’s much harder to work with. Manufacturing involves sintering zirconium-oxide powder (whose granules are roughly one fifth the diameter of a human hair) at temperatures of 1,450C. And the end product is notoriously brittle.