Grand Seiko ‘Unkai’ – SBGH311G Mechanical Hi-Beat Limited Edition


Grand Seiko ‘Unkai’ – ‘Sea of Clouds’ Hi-Beat GMT Limited Edition

There are just 1,200 pieces of this limited-edition design available globally, created to mark the 25th anniversary of the Grand Seiko in-house developed 9S Calibre movement.

The signature textured dial is inspired by the natural phenomenon of clouds surrounding Mt. Iwate near the Shizukuishi Watch Studio where Grand Seiko mechanical timepieces are made. In Japanese the misty scenery viewed at first light from the top of the mountain the ‘sea of clouds’ or ‘雲海= Unkai.’

‘The Nature of Time’ theme features prominently in Grand Seiko watch designs – a Japanese spirituality where each moment is a unique expression unveiled through light and shadow. The watchmakers’ pride in their surroundings is represented from engineering watch movements, to creating dials reflecting the beauty of Japanese nature.

This Hi-Beat watch is powered by the in-house built mechanical Calibre 9S85, with a power reserve of 55 hours and an accuracy rate of +5 to -3 seconds per day. With a 37mm case size, the sapphire crystal case back showcases a sky-blue oscillating weight inspired by the ‘sea of clouds’ design, a colour created through anodic oxidation.

Every Grand Seiko features signature high standards of precision, durability and legibility, handcrafted in Japan by Takumi artisans. Grand Seiko: beautifully, precise Japanese watchmaking, from the pinnacle of Seiko Watch Corporation’s in-house ‘manufacture.’

Reference: SBGH311G

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Grand Seiko ‘Unkai’ – SBGH311G Mechanical Hi-Beat Limited Edition

Grand Seiko ‘Unkai’ ‘Sea of Clouds’ Hi-Beat GMT Limited Edition



  • Exterior: Stainless steel
  • Case back: See-through & Screw case back
  • Glass Material: Dual-curved sapphire crystal
  • Glass Coating: Anti-reflective coating on inner surface
  • Case size: Diameter 37.0mm Lug-to-lug 44.6mm Thickness 13.3mm
  • Band width: 19mm
  • Clasp type: Three-fold clasp with push button release
  • The perimeter of Band: 192mm


  • Caliber no.: 9S85 Instructions
  • Movement Type: Automatic with manual winding
  • Power reserve: Approx. 55 hours
  • Mean daily rate: +5 to -3 seconds per day
  • Mean daily rate is a mean value of daily rates in a condition where the movement before assembly in a case is measured in six positions in a fixed manner under artificially controlled environment for 12 days.
  • Normal Usage Accuracy: +8 to -1 seconds per day


  • Water resistance: 10 bar
  • Magnetic resistance: 4,800 A/m
  • Weight: 142 g
  • LIMITED EDITION on the case back
  • Serial number engraved on the case back
  • 37 jewels

Reference: SBGH311G



Additional information


Grand Seiko




Stainless Steel

Watch Movement

Mechanical Hi-Beat