Glossary · Regulation
Silicon hairspring
A balance spring etched from silicon, non-magnetic and largely insensitive to temperature when coated.
Explanation
Silicon hairsprings are etched by photolithography from monocrystalline silicon wafers. They are non-magnetic, need no lubrication, are largely temperature-stable and can be shaped precisely — including terminal curves impossible to form in metal. Introduced in the early 2000s (Ulysse Nardin, then Patek Philippe, Rolex and the Swatch Group), they are a major modern materials change, though brittle to shock in handling.