Seiko

Before Seiko created Spring Drive, we had two choices -- a mechanical watch with traditional character and autonomy (and relative imprecision) OR we got an electronic or quartz watch that was up to ten times more accurate (but required a battery). 

In 1999, Spring Drive offered a solution to this dilemma by combining the  two technologies in a watch powered by a mainspring with electronic escapement that offered accuracy of one second a day. 

Now, two decades on, Grand Seiko introduces a new generation Spring Drive caliber that is 15% slimmer, 50% more precise and has 60% greater power reserve. Caliber 9RA5 takes Spring Drive technology to a new level of excellence and opens a new era in the history of Grand Seiko.

Caliber 9RA5 offers enhancements in every aspect of its performance and finish

The Grand Seiko team aimed to create a Spring Drive watch that, in size, performance and functionality, would set a new standard for any spring-powered watch.

Caliber 9RA5. A slim Spring Drive movement with power and strength

Compared to the current 9R6 caliber, Caliber 9RA5 delivers a five-day power reserve, an increase of 60%. Its precision has improved from ±15 seconds to ±10 per month! Movement thickness is reduced from 5.8mm to 5.0mm (and the speed of the date change has been greatly increased).

Offset Magic Lever for thinness

Caliber 9RA5’s thin profile is partially due to re-positioning of the Magic Lever. Developed in 1959, the Magic Lever boosts the efficiency of a automatic winding mechanism, using movement of the oscillating weight in both directions. The new Offset Magic Lever is positioned away from the center of the movement to reduce its thickness, with no loss of winding efficiency. The stem and crown are moved towards the back of the case to lower the center of gravity and achieve a comfortable fit on the wrist.

One-piece Center Bridge for rigidity

Caliber 9RA5 is slim but it has enhanced rigidity and shock resistance thanks to the new layout of the gear train towards the center of the movement and a stronger central bridge. This One-piece Center Bridge achieves a shock resistance that meets the ISO standard for diver’s watches.

Dual-size Barrels for 120 hours

The movement uses two mainspring barrels to deliver a 120 hour power reserve. They are different sizes to deliver the enough torque for the five day power reserve while optimizing space within the movement.

New Integrated Circuit for greater precision

Caliber 9RA5 has an accuracy rate of ±10 seconds/month thanks to a new IC package using highly-stable quartz oscillators that have gone through a three-month aging process. This is the first Spring Drive with a sensor to measure the temperature within the movement and compensate for any temperature-induced inaccuracies in the oscillation rate. The oscillator and sensor are vacuum-sealed together to eliminate even the slightest temperature difference between the two, and to reduce influence of humidity, static electricity or light.

Movement inspired by nature, in form and function

The 9RA5’s seconds hand moves in perfect glide motion and expresses the natural and continuous flow of time. The movement has a beauty that is uniquely Japanese and is inspired by the natural environment of the studio where it is made. The jewels echo the glittering stars that sparkle especially brightly during the early days of winter in the surrounding mountains and the delicate texture of the movement’s surfaces reflect the frost that winter brings to the trees.

Caliber 9RA5 makes its debut in a professional diver’s watch

To demonstrate its power, strength and precision, the first creation powered by Caliber 9RA5 is a professional diver’s watch. It has helium and water resistance that meet the challenge of saturation diving at depths of up to 600 meters. The case is in high-intensity titanium, which is 40% lighter than steel and more impervious to scratches. 

The power reserve is at the 10 o’clock position and the indicator is divided into five parts to show exactly and clearly how many days of power are left. The case, crystal and bezel are all designed for easy and safe disassembly for the maintenance that a professional diver demands. It is a watch entirely worthy of the high performance of the new caliber that powers it.

Presentation

The watch is presented in a special Grand Seiko 60th anniversary box with an interchangeable blue silicone strap. It will be available worldwide in August as a limited edition of 700.

Grand Seiko 60th Anniversary Limited Edition Professional Diver’s 600M

Spring Drive 5 Days Caliber 9RA5

Driving system: Automatic

Power reserve: 5 days (120 hours)

Accuracy: +/-0.5 seconds per day (+/-10 seconds per month)

Number of jewels: 38

Diameter: 34.0mm, Thickness: 5.0mm

Specifications

High-intensity titanium case and bracelet

High definition sapphire crystal

Screw-down crown, screw case back

Water resistance: 600m saturation diver’s

Magnetic resistance: 4,800 A/m

Diameter: 46.9mm, Thickness: 16.0mm

Three-fold clasp with push button release, secure lock and extender

Approximate recommended retail price in Europe: €11,500

Limited edition of 700

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