Grönefeld One Hertz Hertz Classic Collection

Introduced in 2010 by Dutch watchmakers Bart and Tim Grönefeld, the One Hertz is the world’s first and only series wristwatch with independent dead seconds. The One Hertz is a prize-winning timepiece. It was awarded the Innovation prize in the 0024 WatchWorld Watch of the Year contest in 2011 and was voted Watch of the Year in 2011 by members of the influential watch forum Timezone. The One Hertz Hertz Classic features five exclusive limited editions: Platinum, Titanium, Ruthenium, Dune and 1912.

The One Hertz Hertz Classic collection features five exclusive limited editions:

The One Hertz Platinum: The One Hertz Platinum features an exclusive platinum case and cool blue dial. The ensemble of indications is all the more striking thanks to the sophisticated blue dial background which perfectly complements the regal tones of the precious metal platinum case.  Limited edition of 12 pieces.

One Hertz Platinum

The One Hertz Titanium: The One Hertz Titanium features a high-tech, polished and brushed titanium case as well as a fresh white micro-guilloched dial.  Limited edition of 30 pieces in polished and brushed grade 5 titanium.

One Hertz Titanium

The One Hertz Ruthenium: The One Hertz Ruthenium features a titanium case and sleek, dark ruthenium dial. Limited edition of 30 pieces in polished and brushed grade 5 titanium with ruthenium dial.

One Hertz Ruthenium

The One Hertz Dune: The One Hertz Dune features a sophisticated red gold case and stylish brown dial. Limited edition of 20 pieces in red gold.

One Hertz Dune

The One Hertz 1912: The One Hertz 1912 features a stainless steel case and stylish monochromatic grey dial. It is so named because 1912 was the year Bart and Tim’s grandfather Johan Grönefeld qualified as a watchmaker. Limited edition of 12 pieces in stainless steel.

Technical details

Collection: One Hertz Classic

One Hertz Platinum – limited edition of 12 pieces featuring platinum case
One Hertz Titanium – limited edition of 30 pieces featuring polished and brushed grade 5 titanium case
One Hertz Ruthenium – limited edition of 30 pieces featuring polished and brushed grade 5 titanium case with ruthenium dial
One Hertz Dune – limited edition of 20 pieces featuring red gold case and security screws
One Hertz 1912 – limited edition of 12 pieces featuring stainless steel case (Now sold out)

Features and indications
Independent dead seconds – large dial at 7 o’clock
Hour and minutes – subdial at 2 o’clock
Power reserve indicator at 12 o’clock of seconds ring
Innovative Winding-Setting mechanism
Winding-Setting indicator at 3 o’clock
In-house calibre G-02

Case and dial
Case: Polished bezel and centre band with hand-finished straight graining; sapphire crystal on the front is slightly domed with anti-reflective treatment on both sides; sapphire crystal on the back is flat with anti-reflection treatment on the inside; engraving of serial number and model; 8 security screws
Number of case components: 68
Case dimensions: Diameter: 43 mm; thickness: 12.5 mm
Water resistance: 3atm/30 meters/100 feet
Crown: Engraved with “G” logo and push to set/wind function
Seconds chapter ring: Made of sapphire
Strap: Hand-sewn, alligator leather with tang buckle engraved with the Grönefeld logo

Calibre G-02: Mechanical hand-wound movement; independent dead seconds
Movement dimensions: Diameter 15 1/4’’’ 9.5 mm; thickness: 34 mm
Number of components: 285 in the whole movement
Number of jewels: 39 jewels in gold chatons
Power reserve: 72 hours
Barrels: 2 barrels, one for the going gear train and one for the independent dead seconds mechanism; both barrels are wound at the same speed and in the same direction
Balance wheel: Free sprung variable inertia balance wheel (9.12 mm diameter)
Frequency: 21’600 vph
Balance spring: Phillips terminal overcoil curve; triangle-style stud
Escapement: Swiss lever escapement
Mainplate: Spotted and snailed rhodium plated nickel silver
Bridges: Hand bevelled; stainless steel X46 Cr13 Micro-blasted centre; circular grain on the top; relief engraved in the micro blasted surface
Gearing: Two gear trains with their own energy sources (2 barrels)
Dead seconds: Independent mechanism; cam with 30 teeth on the fourth wheel of the going geartrain; special escape wheel on the fourth wheel of the independent geartrain; double lever with four jewelled pallets
Winding-setting: Crown with push function to choose between winding or setting
Power reserve: Classic Breguet mechanism by means of a cone moving up and down on the threaded barrel arbour

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