Grand Seiko 5646-7010 Hi-Beat (February 1972)

Excellent original condition – Suwa production, caliber 5646 with day of the week display (Kanji/English)

This Grand Seiko, reference 5646-7010 , from February 1972 (serial number 273526), ​​is among the most precise automatic watches of its time. It comes from the renowned Suwa Seikosha factory , the cradle of the classic Grand Seiko models of the 1970s.

The watch is in exceptionally good condition: the silver-white dial is clear and flawless , the case edges are sharp and unpolished , and the watch has recently been professionally serviced by a Japanese watchmaker .

The built-in Calibre 5646A is a high-frequency automatic movement with 36,000 vibrations per hour and features a day and date display with a bilingual day of the week (Japanese/English). It is one of the last purely mechanical Grand Seiko movements before the quartz era and is distinguished by its legendary accuracy.

Technical data

• Brand: Grand Seiko (グランドセイコー)
• Reference: 5646-7010
• Serial number: 273526
• Caliber: 5646A Hi-Beat Automatic, 36,000 A/h, Date & Day of the Week (Kanji/English)
• Production period: February 1972
• Origin: Suwa Seikosha, Japan
• Case: Stainless steel, screw-down case back with gold Grand Seiko plaque
• Case diameter: approx. 36.2 mm
• Height: 10.6 mm
• Lug-to-lug: 41.3 mm
• Lug width: 18 mm
• Strap: new black leather strap (centfill) with alligator embossing
• Weight: approx. 50 g (including strap)
• Dial: Silver-white, applied indices, day/date display at 3 o'clock
• Crown: Original GS crown
• Glass: curved mineral glass
• Water resistance (originally): Water Resistant (not tested)
• Condition:
  • Dial in near-perfect original condition
  • Sharp, unpolished case edges
  • Movement overhauled, runs precisely
  • Gold medallion on the case back with age-appropriate patina

Special features

• Hi-Beat caliber (36,000 A/h) – extremely precise automatic movement
• Dual calendar display (day/date) with kanji weekdays
• Original GS crown and gold baseplate preserved
• Unpolished case with clean edges – exceptional for its age
• Professional auditing in Japan
• Classic Grand Seiko design based on the "Grammar of Design" by Taro Tanaka

Historical background

The Caliber 56GS (5645/5646) was one of the last purely mechanical Grand Seiko series before the introduction of quartz movements in 1973. These models combined top technical performance with a clear, angular design based on Taro Tanaka's "Grammar of Design" – a design language that continues to define Grand Seiko to this day.

With 36,000 vibrations per hour and a day/date function, the Caliber 5646A set new standards for accuracy and everyday usability. The models from the Suwa factory of this era are considered technically sophisticated and aesthetically perfect classics .

Warranty (used)
This is a used item. The limitation period for claims based on defects (statutory warranty) is 12 months from delivery.

Notice
As this is a vintage watch, water resistance cannot be guaranteed. To protect the movement, the watch should not come into contact with water or moisture.