Grönefeld One Hertz – Watch of the Year

 Grönefeld One Hertz – Watch of the Year

Gronefeld one Hertz Watches

The Grönefeld One Hertz features a completely original in-house developed movement indicating hours and minutes on a sub-dial at 2 o’clock, a large sub-dial for the deadbeat seconds filling the majority of the dial with a power reserve indicator at 12 o’clock, and a setting-winding indicator at 3 o’clock. Setting-winding is ergonomically selected by pushing the crown instead of pulling it out.

With the One Hertz’s unique secondary gear train, Tim and Bart Grönefeld have re-positioned the deadbeat seconds complication where it originated, i.e. on the pedestal of high precision.

The quartz-like movement of the large second hand of the One Hertz subtly signals its unique mechanism, invisible to most, but obvious to haute horlogerie aficionados who will appreciate the flawless fine-finishing of the in-house developed calibre G-02.

The One Hertz launched in 2010 with a subscription-only limited edition of 12 pieces in steel called the “One Hertz 1912” – 1912 was the year Tim and Bart’s grandfather qualified as a watchmaker. 2011 heralded the One Hertz Dune, a limited edition of 20 pieces in red gold and 2012 saw the launch of the One Hertz Platinum in a limited edition of 10 pieces.

Technical specifications:

Calibre G-02, mechanical hand winding, independent deadbeat seconds, power reserve indicator and setting indicator


  • Number of parts: 285
  • No.of jewels: 39, set in gold chatons
  • Power reserve: 72 hours, classic Breguet mechanism of cone moving up and down the treaded barrel arbor
  • Balance wheel: 9.12mm free-sprung variable inertia balance wheel
  • Frequency: 21’600 bph/3 Hz
  • Balance spring: Phillips terminal overcoil curve, triangle-style stud
  • Deadbeat seconds mechanism: Independent mechanism, cam with 30 teeth on the going gear train on the seconds wheel, escape wheel on the seconds wheel of the independent gear train

Case and dial

  • Material: Brushed and polished grade 5 titanium.  Limited edition of 30 pieces Sapphire crystal on the front is slightly domed and coated on both sides Sapphire crystal on the back is flat and coated on both sides Engraving of “Titanium”, “Limited 30 pieces” and the serial number Stainless steel security screws Polished bezel and centre band with hand-finished straight graining
  • Dimensions: 43mm x 13mm
  • Water resistance: 3atm/ 30m/ 100feet
  • Dial: Hour and minutes sub-dial, seconds sub-dial, power reserve indicator, setting-winding indicator
  • Hands: Hours and minutes, long thin counter-poised seconds, power reserve and setting-winding
  • Strap and buckle: :  Hand-sewn matt black, orange stitching, alligator leather with steel buckle, engraved with the Grönefeld logo

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