Nickel is one of the most present elements in watchmaking, often without the wearer knowing it. It plays a role in very different contexts: as a structural component of metal alloys, as a material for micro-components produced with LIGA technologies, as a chemical element responsible for allergic reactions, and as an involuntary protagonist in meteorite dials.
In stainless steel alloys — both 316L and 904L — nickel is the addition that produces the austenitic crystal structure: without it, steel would not have that corrosion resistance and workability that make it suitable for watchmaking. The 904L, used by Rolex, is notably richer in nickel compared to standard 316L; this affects the thermal conductivity and some sensory properties of the metal. Even 18k gold can contain nickel, often in less noble white or yellow versions, where it enters as a hardener in place of palladium.
Maillechort — an alloy of copper, zinc and nickel also known as German silver — is used for plates and bridges in some high-end movements. A. Lange & Söhne employs it traditionally; Armin Strom and Ulysse Nardin have made it a declared aesthetic choice. Nickel gives the alloy a warm, silvery reflection, and in theory develops a patina over time, although in a sealed movement this process is very slow.
With LIGA technologies — an acronym for Lithographie, Galvanoformung, Abformung — pure nickel is deposited galvanically in layers with sub-micrometric precision. This is how components such as the balance wheel flyweights in Ulysse Nardin's UN-230 caliber, or the micro-blades that stabilize the large-diameter silicon balance wheel in the Freak are produced: pieces that could not exist with traditional mechanical processing.
In ferrous meteorite dials, nickel is one of the main ingredients of the crystal structure. The Widmanstätten patterns — those lines crossed at 60° visible on the Muonionalusta, for example — are formed precisely by the segregation of iron and nickel during extremely slow cooling in space. They are made visible with acid etching, usually nitric.
On the allergy front: nickel is one of the most common contact haptens. This is why titanium and ceramic are often proposed as alternatives to steel, precisely because they lack it. The nickel plating on the 30T2 movements from World War II has, finally, a precise historical value: copper was rationed for military use, so the finish changes color and becomes an indicator of wartime production.