Brotherly love

The two Dutch brothers, Tim and Bart Grönefeld fooled me into thinking the “One Hertz” nomen, referred to the frequency of the balance wheel. It actually refers to the dead beat seconds, sometimes referred to as “second morte” or “jumping seconds” on their Dune model.

Independent’s day - Grönefeld “One Hertz” Dune

I am hopeless a cook. If I open a tin of baked beans and place them in a pan, it is inevitable they will become a congealed mass within two nano seconds. I don’t know why I am hapless with food preparation, my substantial waistline may fool the casual observer into thinking that I am a culinary genius.

My domain, is writing about watches. I fall into horological parlance as a matter of routine. It does not endear me to those philistines who fail to appreciate the emotional appeal of haute horology, but I don’t care. My life is dominated by a compunction to wax-lyrical about finissage, complications, enamelling and such matters.

I often look at specifications of wrist watches and record details of movements such as number of parts, jewels, power reserve and frequencies. Indeed, it is frequencies of 2.5, 3, 4 and 5 Hertz I typically note. There are some watches which have higher frequencies but these are few and far between.

My incredulity was heightened, when I saw a press release for the Grönefeld “One Hertz” Dune. The apparent lack of vibrations per hour appeared to be contrary to the recent trend adopted by some brands for dizzyingly fast frequencies. However, all was not as it first appeared.

Independent’s day - Grönefeld “One Hertz” Dune

The two Dutch brothers, Tim and Bart Grönefeld fooled me into thinking the “One Hertz” nomen, referred to the frequency of the balance wheel. It actually refers to the dead beat seconds, sometimes referred to as “second morte” or “jumping seconds”. The second hand moves in one second increments, hence the name. The motion of the seconds hand resembles the advancing hand of a quartz watch. But, this is no quartz watch but a mechanical timepiece created in an atelier in The Netherlands by a small team of artisans.

The complication of a dead beat seconds may not sound remarkable to those naive about horological matters. Yet, this complication is incredibly complex, necessitating immense skill and ingenuity.

The seconds hand on the “One Hertz” remains stationary, until a full second has elapsed and then jumps to the next integer on the chapter ring.

This model features two spring barrels, one to power the hours and minute hands, whilst the other spring barrel drives the independent dead beat seconds.

In some watches equipped with a dead beat seconds complication, the tension, which accrues prior to the second hand jumping to the next integer, can create “turbulence” accoring to Bart. However, the “One Hertz”, thanks to the twin spring barrels, two gear trains and three-armed anchor, the complication does not impair the chronometric precision of the timepiece.

The dial

The “One Hertz” Dune is presented with a chestnut dial, contrasting charmingly with 18-carat 5N rose gold.

Independent’s day - Grönefeld “One Hertz” Dune

An off-centre hour and minute display is located at 1 o’clock. It has a snailed centre, framed with a black chapter ring. Applied, metalized, triangular shaped batons indicate the hours. Dauphine shaped hands, presented in a golden hue, convey the hours and minutes.

A larger dial spans the aforementioned hour and minute display. It is constructed of sapphire with metalized indices against a black chapter ring. It is mounted to the main dial utilising four screws. The snailing is repeated, save for the area occupied by the power reserve-indicator.

Independent’s day - Grönefeld “One Hertz” Dune

The power reserve is presented on a smooth area using a crescent shaped scale and slim gold coloured hand, to indicate the energy stored within the twin barrels.

Adjacent the crown, the design code of the power reserve is repeated. This time a hand shows “S” and “W”. The text refers to “Setting” and “Winding”. By simply pushing the crown, the wearer can switch between setting and winding.

Two cartouches feature at 4 o’clock and 10 o’clock. They are engraved, “One Hertz” and “Grönefeld” respectively.

The case

The 43mm case diameter will provide universal appeal to the majority of potential wearers. The upper surface of the bezel and lugs is highly polished. The caseband is satin brushed, with fine, straight graining, deftly applied by hand.

Independent’s day - Grönefeld “One Hertz” Dune

The caseback is fitted with a sapphire crystal, indulging the wearer with a view of the exceptional hand finished movement.

Gold screws secure the caseback in position. The slots are flawless and testament to the perfectionism practised by the Grönefeld team.

The movement

I have already discussed the complexity of the dead-beat complication on this watch, but there are many additional aspects which distinguish this timepiece as a paragon of craftsmanship.

Independent’s day - Grönefeld “One Hertz” Dune

The movement comprises 285 parts all beautifully presented. The Caliber G-02 has 39 jewels, each one mounted in a gold chaton.

At first glance the movement appears modern, courtesy of the avant-garde micro-blasted treatment to the bridges. However, close examination reveals hand beveled edges to the stainless steel bridges. Moreover, they are spotted underneath and presented with circular graining on their upper surfaces.

Independent’s day - Grönefeld “One Hertz” Dune

Independent’s day - Grönefeld “One Hertz” Dune

Independent’s day - Grönefeld “One Hertz” Dune

The brand name and number of jewels, are relief engraved on the bridges. Nothing ever appears to be conceived for expedience or to make the brothers lives easier.

In theory, a dead-beat seconds should consume more energy than a regular timepiece, but this watch has twin barrels. This results in an impressive 72 hour power reserve.


Those of inquiring disposition may query my choice of title. I have no doubt Tim and Bart do love each other. However, it is the love they bestow to their watches, to which I refer.

If you study every aspect of their watches, it soon becomes apparent that they are the antithesis of mass production. Their relentless obsession with detail is tangible as you study the flawless finissage and elevated engineering.

It comes as no surprise that they only produce limited numbers of watches. It would be difficult to imagine how they could make these watches, embracing less labour intensive methods, without sacrificing their cherished high standards of work.

Independent’s day - Grönefeld “One Hertz” Dune

I would dearly love to own a Grönefeld timepiece, but sadly the most accessible model, presented in stainless steel is now sold out. The watches represent value compared to many offerings from mainstream brands, yet proffer exclusivity for those seeking no-compromise creativity.

I dream of the day, when I can order a Grönefeld “One Hertz” and enjoy the brotherly love that is exampled with these watches.

Technical specification

  • Model: Grönefeld “One Hertz” Dune
  • Case: 18-carat 5N rose gold case; diameter 43.00 mm; height 12.50 mm; water resistant to 3 bar (30 metres); sapphire crystal to the front and caseback.
  • Functions: Hours; minutes; dead-beat seconds; power-reserve; settting-winding indicator.
  • Movement: Calibre G-02; Hand wound movement; frequency 21,600 vph (3 Hz); 39 jewels; power reserve 72 hours; 285 parts.
  • Strap: Black alligator leather strap with 18-carat 5N rose gold pin buckle.
  • Limited Edition: 20 pieces

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