After 60 years of making some of the industry’s most innovative and exacting movements, it may surprise some to learn that Grand Seiko has only just released its first mechanical chronograph, the Evolution 9 Tentagraph SLGC001. That isn’t to say the Japanese watchmaker didn’t know how to — it was just making them using its famous Spring Drive technology, which combines mechanical movements with electronic regulators in order to deliver extraordinary precision. The arrival of the Tentagraph is merely a new expression of the brand’s know-how, and a natural follow-up to the Evolution 9 collection’s first mechanical complication last year, the GMT.
The name rolls off the tongue, but its purpose was really to highlight the watch’s many features. The “ten” refers to the watch beating at 10 beats per second, the following “t” and “a” represent
three days of power reserve and automatic movement respectively, and the “graph” of course refers to the chronograph.
The new 9SC5 movement is not an integrated movement, but rather a chronograph module built upon the feature-packed 9SA5 that first appeared in the 60th Anniversary Limited Edition SLGH002 in 2020. Among its many horological upgrades are a high-beat 5Hz frequency, a dual impulse escapement (designed to reduce friction and energy loss), double barrels, a free-sprung balance, instantaneous date change, and an accuracy rating of +5/-3 seconds a day.
The movement’s two barrels are especially useful for the Tentagraph, as its three-day power reserve is now the longest on the market for a high-frequency chronograph. The chronograph module also uses a column wheel and vertical coupling for smooth and snappy activation of the chronograph hands, as well as a three-pointed hammer that ensures the hands reset to zero instantly and in perfect synchronization.
Watches that run at high frequencies are fairly uncommon due to the strain placed on the movement’s parts, which results in the need for more durable ones and better lubricants, but Grand Seiko puts every 9SC5 through its paces to ensure reliable functioning. The movement is tested for accuracy in six positions and three temperatures for 17 days, before going through another three days of testing in three positions while the chronograph is running.
The movement's exceptional craftsmanship finds its match in an equally impressive case design. Crafted in dimensions of 43.2mm by 15.3mm, the casing is constructed from what Grand Seiko terms "high-intensity titanium," a material reputed to be stronger than Grade 2 titanium and capable of achieving a lustrous polish. Much of the surfaces are brushed, though the bevels on the case sides have been Zaratsu polished. With a screw-down crown enhancing its water resistance to 100 meters, the watch boasts practicality. The classic tri-compax layout sits on a dial decorated with a sunray-like pattern inspired by Mt. Iwate in a rich blue hue and is topped with a box-shaped sapphire crystal. The polished and brushed black ceramic bezel perfectly rounds off the Tentagraph's dynamic and sporty appearance.
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