Grand Seiko is a brand that was founded on being better. At one point, it represented the highest version of Seiko in terms of watchmaking, imagining what a luxury Japanese timepiece would be. Today, it has since branched off to become its entity, keeping the ethos of making fantastic luxury Japanese watches with the highest level of craftsmanship. Beyond that, however, there was, and is, a quest for Grand Seiko to achieve the utmost level of timekeeping precision. This year marks the next step the brand is taking with the new Spring Drive Ultra Fine Accuracy (U.F.A) SLGB003.
Just as a little bit of a backgrounder, Grand Seiko’s Spring Drive technology is their effort to combine the precision of a quartz oscillator with a mechanical soul. It was developed at a time when quartz movements were disrupting the industry and by 2004, when it was first unveiled, the world was ready to accept that mechanical timekeeping was its form of luxury.
The basic premise of the Spring Drive movement is that it uses a mainspring to power a geartrain as per any mechanical watch. The difference is that instead of a traditional escapement system to regulate the release of power from the mainspring, it uses a quartz oscillator and a braking system to ensure that the seconds hand glides ever so smoothly, making one full rotation of the dial in 60 seconds.
As a comparison, a chronometer certified by COSC has to be accurate to within -4/+6 seconds per day and Rolex does a -2/+2 seconds per day accuracy for their Superlative Chronometer. Spring Drive already beats that with -10/+10 seconds per month. And now, with the U.F.A., Spring Drive is capable of reaching an accuracy rate of -20/+20 seconds per year. Yes, per year! That is 3 seconds per month and about 0.1 seconds per day. This makes the Spring Drive U.F.A. the most accurate wristwatch powered by a mainspring ever.
To achieve this stunning accuracy, the calibre 9RB2 movement combines a newly designed integrated circuit (IC) and a new three-month-aged quartz oscillator. As with the previous generation of Spring Drive movements, the frequency of each quartz oscillator is measured at different temperatures and the data is fed into a temperature compensation programme within the low-power IC.
The entire thing is then vacuum sealed to protect against external factors such as humidity, static electricity, and light. For such finely controlled accuracy, however, the new calibre 9RB2 is fitted with a new regulation switch that after-sales personnel can use to correct any divergence in accuracy.
Beyond the fantastic movement, the aesthetics of the Spring Drive U.F.A watch also bring with it a unique appeal. First of all, it measures 37mm in diameter, making it the smallest case size to use a 9R movement to date. The case and bracelet of the SLGB003 are made of High-Intensity Titanium, which, as you can imagine, was incredibly difficult considering that all Grand Seiko cases have some form of Zaratsu mirror-polished surfaces. Not forgetting the dial, this incredible pattern was inspired by the Kirigamine Highlands east of the Shinshu Watch Studio, where frost-covered trees stand majestically during the harsh winter months.
This story was first seen as part of the WOW #79 Summer 2025 Issue
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