Grönefeld One Hertz 1912, Stainless Steel

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


The Grönefeld brothers’ upbringing in a small town in the Eastern part of the Netherlands was permeated in horology. 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 a few dozen watches a year, the Grönefeld brothers create extremely high-quality pieces, having commanded the admiration and respect of none other than Philippe Dufour, amongst others.

Providing a more constant delivery of energy to the escapement, a remontoire in theory offers greater precision. Celebrated watchmaker Dr George Daniels, describes the complication in his book, Watchmaking: “The use of the remontoire is by far the best method of smoothing the power supply, but it is complex and costly to make. For this reason watches with remontoires are very rare, and this, combined with their attractive action, gives them a special place in the affections of the connoisseur of mechanics. The fact that the mechanism is quite unnecessary merely adds to its charm.”