During a period of adjustment, we're unable to ship watches to the EU. There may also be a slight delay to deliveries of straps & accessories. Apologies for any inconvenience caused.

Grönefeld
1912 One Hertz | steel

One of twelve

Regular price


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Grönefeld
1912 One Hertz | steel

One of twelve

Regular price


This steel, Grönefeld 1912 One Hertz is one of the earliest wristwatches made by the brothers, after their Tourbillon Minute Repeater. Designed by the Grönefeld brothers in the Netherlands, the One Hertz movement was developed with the assistance of famed complications specialist Renaud and Papi in Switzerland, where Bart and Tim Grönefeld spent a number of years at the heart of the manufacture. Though subsequent pieces have since been made in a range of case materials, the One Hertz was initially launched in 2010, with a limited production of just 12 pieces in steel.

The Grönefeld brothers

The Grönefeld brothers’ upbringing in a small town in the Eastern part of the Netherlands was permeated in horology. In the evenings and on the weekends, as children, they used to play in their grandfather Johan's workshop, surrounded by instruments and by the sound of their ceaseless ticking. As a gifted watchmaker, Johan also looked after the clock of the nearby church, dating back to 1240. On his death, this custodianship was passed onto his son, the Grönefeld brothers’ father. The year the Grönefeld name was established in watchmaking was commemorated in the reference of the '1912 One Hertz'.

Watchmaking having made a strong imprint on them in their respective youths, Bart and Tim Grönefeld both trained in horology, cutting their teeth at famed complications specialist Renaud et Papi, alongside notable contemporaries such as Stephen Forsey and Stepan Sarpaneva. Producing no more than 70 watches a year, the Grönefeld brothers create extremely high-quality pieces, having commanded the admiration and respect of none other than M. Philippe Dufour, amongst others.

The One Hertz Movement 

One of the more obscure complications in horology, the 1912 One Hertz incorporates a deadbeat seconds, rarely found in contemporary watchmaking. An interesting complication for the brothers to tackle early on, the original deadbeat escapement goes all the way back to 1675, when it was invented by Richard Towneley for use in regulator clocks at the Greenwich Observatory. The complication itself is demonstrated through the jumping seconds snapping into position, contrary to the majority of mechanical watches where the second hand glides smoothly between passing seconds. Specialists in complicated watches, the Grönefeld’s intent to follow their Tourbillon Minute Repeater with a simple, time-only watch was always going to evolve into something mechanically more intriguing.

In the case of the One Hertz, Bart and Tim designed their movement to operate using two gear trains, based on two synchronised spring barrels feeding two separate (but linked) movements – one for the hours and minutes and the other for the seconds. According to Bart Grönefeld, the parts for the One Hertz movements were machined by Renaud et Papi in Switzerland, before being shipped to the Netherlands to be finished, painstakingly decorated and assembled in the Grönefeld workshop. The movement features over a dozen different finishing techniques, from snailing to frosting. The bridges, shaped like the bell gable roofs of Dutch houses, are fashioned out of steel, which is much more difficult and costly to work with, than brass or silver.

Each individual bridge requires dozens of steps and up to ten hours of work, including mirror polishing of the screws, and chamfering rims and slots, demonstrating the brothers’ fascination with depth and light. The overall dimensionality is reminiscent of A. Lange & Söhne, or even fellow Renaud et Papi alumni Greubel Forsey.

A coherent design

In traditional fashion, the Grönefelds imagined their desired dial layout first, before figuring out how to make a suitable movement to match. The deadbeats seconds occupies a central place, emphasised through the large seconds sub-dial - a sapphire disc raised above the other indications and metallisised. By comparison, the subsidiary dial for the hours and minutes are discretely located above, extending within the seconds indication. The overlapping portion of the sapphire disc is transparent, so as to not obscure the hours and minutes.

Encased within the large seconds sub-dial is the recessed power reserve indicator, highlighted by a frosted surface. The crown position indicator for “winding” and “setting” is similarly textured. Toggling between the two modes involves using the push-button crown, hacking the movement during setting - a system reminiscent of the clutch mechanism found in a number of Richard Mille models, also machined early on by Renaud et Papi.

The case, measuring 43mm across and 13mm thick, is made out stainless steel. It features brushed case sides, with polished caseback and bezel portions, giving the One Hertz a classically finished appearance. Despite its imposing size, it wears comfortably on the wrist, owing to the choice of case material and downturned, sculpted lugs.

The Set

This steel, Grönefeld 1912 One Hertz is accompanied by its original box and paperwork. It comes on a bespoke Helsinki grey nubuck leather strap, with curved ends, and also includes the original alligator strap and Grönefeld steel buckle.

Brand: Grönefeld
Model: 1912 One Hertz
Movement: manual-winding Caliber G-02
Functions: hours, minutes, seconds, power-reserve
Features: deadbeat seconds, push setting crown, two barrels
Case: 43mm stainless steel
Crystal: sapphire front and back
Strap: Helsinki nubuck leather strap; Grönefeld alligator strap and steel pin buckle
Lug/buckle width: 20/16 mm
Year: 2010
Box & papers: full set - box, papers & guarantee card
This Grönefeld 1912 One Hertz watch comes as a full set, with its original box and papers. The watch is in excellent condition and has perfect mechanical functionality. It's guaranteed for authenticity, and comes with a two-year warranty from A Collected Man.

All of our pre-owned watches have undergone thorough mechanical inspections, including being ultrasonically cleaned, serviced and resealed if appropriate and tested for at least four days, to ensure they meet our highest timekeeping standards. Our pre-owned and vintage watches, unless stated otherwise, are covered by a full or a limited twenty-four month warranty. For example, due to their age, some vintage watches should not be subjected to the same conditions as when they were new. Please see our Terms & Conditions for further information. 

All of our new watches are covered by the warranty from the original manufacturer. Please contact us for further information.

During a period of adjustment, we are unable to ship watches to the EU. We continue to offer express delivery to all other countries.

If ordering from the UK before 1 PM, your watch will be sent the same working day. The courier will depend on the value of the watch, with all watches delivered the next working day.

If ordering from outside Europe, delivery will depend on choice of courier and destination. 

Please note that pre-owned goods (in the United Kingdom) are subject to a marginal rate of VAT, which can not be reclaimed. For further information, please see here.

You can cancel your order without giving any reason, within 14 days from the day the watch has been delivered to you.

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