Chapter 4

The mainspring, the power behind the precision

The power to move the hands of every Grand Seiko mechanical watch comes from its mainspring. When the watch is worn continuously, the mainspring is in constant use, winding and unwinding several hundred times a year.

So that they deliver a consistent amount of power over the long term, these mainsprings need to be strong and durable. This is why all Grand Seiko Caliber 9S mainsprings are made in-house, using SPRON alloys that are designed specifically for the purpose.

These cobalt-nickel alloys allow the springs to be made to thicknesses of around 0.1mm and so be long enough to deliver all the power required to drive the watch.

Grand Seiko is one of the very few watch manufacturers in the world to make both hairsprings and mainsprings, as well as all other key components, in-house. It is thanks to this expertise and to the company’s long tradition of high-level craftsmanship that Grand Seiko can offer timepieces of such lasting precision.