On the Spring Drive end of the new Grand Seiko Evolution 9 collection is the Grand Seiko 40mm SLGB011 “Atera Valley” – a name inspired by the Atera River flowing through the Nagano prefecture in Japan.
Its Calibre 9RB2 automatic Spring Drive hybrid movement boasts an incredible accuracy rating of ±20 seconds per year, making it the most precise mainspring-powered movement in the world!
This movement provides 72 hours of running autonomy.
To ensure this precision, both the crystal oscillator and the IC are vacuum-sealed, and the oscillator is stabilised through a unique ageing process.
Vacuum sealing minimises the influence of external factors such as temperature, humidity, static electricity, and light, thereby enabling high accuracy.
Each oscillator’s frequency is measured at multiple temperatures, and the resulting data is programmed into the low-power IC to enable precise thermo-compensation.
The watch also drops the dual-curved sapphire crystals featured on previous GS watches, to adopt the vintage-inspired, box-shaped sapphire crystal format.
It has a vivid green textured dial inspired by the deep trees of the valley surrounding the above-mentioned river, and this is housed in Ever-Brilliant Steel – a premium, highly corrosion-resistant stainless steel alloy developed and used primarily by Grand Seiko.
