Evolution 9 Tentagraph

This Grand Seiko Tentagraph ref. SLGC007 was created in the Evolution 9 Style, a unique design method that combines the spirit of Grand Seiko and the aesthetic beauty of Japan to reach new heights. The dial captures Mount Iwate, topped with fresh snow, a merger of the harsh winter’s crisp blue sky and the subtle blue tint of the newly fallen snow. The deep snowfall is represented by the snow-blue dial color and an embossed pattern inspired by the mountain’s ridgelines. 

Just like every Grand Seiko creation, the pursuit of precision is at the heart of the Tentagraph, whose mechanical chronograph movement features the revolutionary high-beat Caliber 9SA5 as its base. Like Caliber 9SA5, the Tentagraph Caliber 9SC5 beats ten times per second, ensuring high accuracy when measuring elapsed time as well as the time of day. And, thanks to its energy- efficient escapement and two barrels, the watch runs for three days even when the chronograph is in operation, making the Tentagraph the 10-beat chronograph with the longest power reserve in the industry today. Furthermore, the Tentagraph is subjected to a more stringent testing procedure. As with all Grand Seiko mechanical movements, the Tentagraph’s time-of-day accuracy is assessed in six positions and at three temperatures over 17 days but, in addition, there are three more days of testing during which the accuracy is assessed in three positions while the chronograph is in operation. Thus, in total, each Tentagraph movement is tested for 20 days to ensure that it meets the Grand Seiko Standard of +5 to -3 seconds per day.

The movement features the revolutionary Dual Impulse Escapement, which efficiently transfers energy to the free-sprung balance wheel indirectly through the pallet fork and also directly from the escape wheel. MEMS technology ensures extremely precise, lightweight, and highly durable escapement parts and also endows the escapement with increased energy efficiency to achieve a long power reserve. Hallmarks of a high-quality modern chronograph, a vertical clutch and a column wheel ensure high accuracy and operability. The vertical clutch eliminates any shuddering or jumping of the hands when the chronograph is engaged and enhances measurement accuracy, while the column wheel delivers precise control of the chronograph operation. The movement incorporates a three-pointed hammer, which ensures that, when the reset pusher is pressed, the hands return to zero instantly and in perfect synchronization.