Seiko Caliber 6R51 Watch Movement

Manufacturer	Seiko
Caliber Number	6R51
Base Caliber	Seiko 6R55
In-House?	Yes
Movement Type	Automatic, self-winding mechanical
Diameter	Unconfirmed
Height	Unconfirmed
Jewel Count	24
Beat Rate	21,600 vph
Accuracy Rating	-15~+25 seconds per day
Lift Angle	53 degrees
Power Reserve	~72 hours (3 days)
Rotor Style	Ball-bearing
Rotor Winding Direction	Bi-directional
Hand-Windable?	Yes
Anti-Shock Device	Diashock
Hand Count	3
Functions	Central hours; central minutes; central sweeping seconds
Hacking Seconds?	Yes
Country of Manufacture	Made in Japan
Known Models	Seiko Presage Craftsmanship Series Studio Ghibli: Nausicaä Of The Valley (Ref: SPB437) (Add your watch to the comments below…)

The Seiko caliber 6R51 is an 3-hander automatic watch movement found in the Seiko Presage model SPB437.

The special Studio Ghibli watch with this movement were introduced in February 2024 to be made available for purchase in March 2024.

In Seiko’s own words:

“The watch is powered by Calibre 6R51, a new version of Seiko’s high-performance 6R55 movement. Like Calibre 6R55, this new version delivers a power reserve of 72 hours and has the same performance attributes, only without the date display. The new movement was developed to emphasise the beauty of the craft dial that sits above it.” –Source

Seiko 6R51 VS 6R55:

The Seiko caliber 6R51 is based on the cal. 6R55 with the main difference being that the 6R55 has a date at 3:00. The 6R51 is a true no-date, time-only movement (no phantom date).

The 6R51 shares the same user manual as the 6R55 (as well as the 6R5H and 6R5J).

6R51 VS 6R51A:

You may notice that the gold rotor (it is only gold tone, not real gold) is signed with calibre number “6R51A”. The “A” represents the first version of the 6R51. It is simply an evolution/version indicator. “A” is the first version, therefore 6R51 is the same as 6R51A. At the time of this post, 6R51B or 6R51C does not exist.

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