At Geneva Watch Days, TAG Heuer unveiled a hairspring forged not from silicon or metal alloys, but carbon. It might sound like a small switch, but in watchmaking terms, it could be seismic.

There’s change afoot in the watchmaking world, and TAG Heuer is leading the charge. At Geneva Watch Days 2025, the brand debuted a new hairspring (the spring in a watch attached to the balance wheel in the movement, which regulates time) made not of the traditional alloy or silicon, but instead, in carbon. The new moody-black forged-carbon hairsprings arrived in TAG Heuer’s two hallmark designs, the Carrera and the Monaco.

This is big news, as it is silicon that has gradually overtaken the 100-year-old Nivarox alloy as the material of choice for making the component that is the beating heart of a wristwatch, thanks to its stability over a range of temperatures and its imperviousness to the magnetic fields we constantly move through.