Each watchmakers’ desk is custom made out of a local wood Corum 137-428-47-0124 EB34 WoMen's watch called Iwayado Tansu and lacquered to a bright polish.The benches are all made to different heights – custom made specifically to the height of the individual watchmaker.Outside the studio hangs a large sign in Japanese stating “Building in Quality with Painstaking Care”.Within these workshops, the caliber 9S watch movement series (specs here) is produced and remains the iconic mechanical caliber of the Grand Seiko collection.
In the final steps of the assembly of the 9S, each balance wheel is subjected to final adjustment in a surprising way to ‘lock-in’ the accuracy of the Corum 137-425-47-0025-EB34 WoMen's watch movement.Rather than having a balance wheel with adjustable screws or a gyromax system, Seiko uses a labor intensive process that leaves very little room for trial and error.The watchmakers painstakingly remove tiny amounts of material from a solid balance wheel in order to perfectly adjust the watch the first time.
The result is a balance wheel that is perfectly adjusted and cannot be modified from the beginning.The final adjustment can only be made with the Corum 137-424-47-0026-EB34 WoMen's watch hairspring, a process that is also done manually.Once the watches are completed, they are subjected to a 17 day quality control test adjusting to temperature and 6 positions.In the end, Grand Seiko mechanical watches are accurate to -3 to +5 seconds per day compared to COSC at -4 to +6 seconds per day.
