Making and adjusting the perfect hairspring

While some Grand Seiko 9S mechanical watch movements have over 300 components, none has a more critical role in determining precision than the hairspring.

Made of SPRON alloys that are unique to the company and designed expressly for this purpose, the hairsprings are finer than a human hair and coiled so densely and accurately that the spacing between the rings can be as little as one tenth of a millimeter.

All the hairsprings for Grand Seiko's 9S mechanical watches have been designed and manufactured in-house so that the highest levels of performance are assured.

The springs are then adjusted, by hand, by the craftsmen and craftswomen at the Grand Seiko Studio Shizukuishi who are so skilled that they work to tolerances of one hundredth of a millimeter. Working under microscopes, they adjust each hairspring until it achieves a perfect ripple-like pattern when they spin the balance. Then, and only then, are the hairspring and its balance ready to be assembled into the movement and prepared for the ultimate test, the 17-day trial to meet the Grand Seiko Standard.