| Brand | Grand Seiko |
| Caliber Number | 9S85 / 9S85A |
| Movement Type | Automatic (Hi-Beat) |
| Jewels | 37 |
| Power Reserve | 55 hours |
| Vibrations Per Hour | 36,000 vph |
| Hairspring | Spron 610 |
| Shock System | Diashock |
| Features | Hours, minutes, central seconds, date |
| Country of Manufacture | Japan |
| Known Models | SBGR051 |
Seiko in-house caliber 9S85A found in a Grand Seiko automatic watch. The Spron 610 hairspring is anti-magnetic.
The heart of the mechanical watch is its movement. A “10-beat” movement means that the balance, the most important component for determining the accuracy of a watch, vibrates at 10 beats, or oscillations, per second. Mechanical watches, even luxury watches, operate at 5 to 8 beats per second. A higher number of vibrations makes a watch more resistant to shock, controlling fluctuations in dynamic accuracy—the watch’s accuracy while being worn—to keep the time correctly and with stability. Seiko has succeeded in producing the Grand Seiko with a 10-beat movement, caliber 9S85. The watch is highly resistant to disturbance with minimized accuracy fluctuation when worn.
- Read more: 9S85 Self-Winding 10 Beat Movement
- Forum talk: As good as it gets: Grand Seiko 9S85 versus Omega AT 8500
- Forum talk: Grand Seiko 9S85 accuracy after 15 days without stopping
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