Monochrome Watches
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The Armin Strom Gravity Equal Force Ultimate Sapphire Purple

A gorgeous, vibrant purple guilloché mainplate showcases the groundbreaking mechanics of the Gravity Equal Force.

| By Rebecca Doulton | 4 min read |

Armin Strom (1938) has gone down in the annals of watchmaking as a pioneer in the art of hand-skeletonisation. Now in the hands of Serge Michel and master watchmaker Claude Greisler, the independent watchmaking brand with 17 in-house calibres continues the master’s legacy of “transparent mechanics” with showstopping models like its Mirrored Force Resonance and Gravity Equal Force series. For 2024, the Gravity Equal Force model, the first automatic watch with a patented equal-force transmission integrated into the mainspring barrel, returns with a trendy purple hand-guilloché dial (mainplate).

Unveiled in 2019 to mark the brand’s tenth anniversary, the Gravity Equal Force introduced the world to the first stop-work declutch mechanism combined with an automatic movement. This technical tour-de-force – fully explained in this video –  was launched in the brand’s “System 78” sub-collection, designed to offer exceptional, innovative watchmaking at more contained prices. Not only did it mark a technical breakthrough in transmitting a steady flow of energy to the escapement during the entire duration of the power reserve, but it also revealed the mechanics dial-side.

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While the Gravity Equal Force has appeared with diverse outfits, including MONOCHROME’s very own Montre de Souscription with a gorgeous German silver mainplate, the latest model pumps up the colour volume with a gorgeous purple hand-guilloché mainplate by Kari Voutilainen – it seems that purple is the colour of the year

Instead of adding colour to the hours and minutes sub-dial, as we’ve seen in past editions like this Jungle Green model, purple is used for the mainplate, creating a regal yet contemporary background that highlights the mechanical spectacle. Decorated with a barley grain pattern and handcrafted in Kari Voutilainen’s atelier (Comblémine S.A.) with a rose engine lathe, the striking purple colour is applied using a 3D PVD process, reflecting a wide spectrum of tones when it encounters the light.

The asymmetrical layout retains its original configuration with the three openworked finger-style bridges on the right side and the large, off-centred sub-dial for the hours and minutes on the right. Unlike many openworked or skeletonised models, Armin Strom has achieved a strong sensation of symmetry with a series of overlapping circles, almost like a Venn diagram.

Vertically arranged on the right, you have the round aperture for the micro-rotor at 1 o’clock, with its visual counterweight formed by the barrel at 5 o’clock, both connected by a wheel of the gear train. On the left, the sub-dial for the time is made of transparent grey-tinted sapphire crystal for enhanced viewing pleasure, a feature usually reserved for the Gravity Equal Force Sapphire Editions. Not only does the off-centred time dial overlap the three round elements on the right, but it is also intersected by the small seconds counter at 8 o’clock. The faceted and polished hour and minute hands are treated with Super-LumiNova for enhanced legibility.

As with all Amrin Strom watches, the finishings are top-class, with black polished screws, polished countersinks, polished bevels, perlage and different types of graining. The finger-style ruthenium-plated bridges, inspired by those found on pocket watches, are entirely decorated by hand. The undersides of the bridges are first given a matte finish. This is followed by a straight-graining finish on the sides using abrasive diamond paper. The penultimate step involves gentian wood to remove the finest lines before giving the bridges their final straight-graining finish.

The stainless steel case retains its 41mm diameter and height of 12.65mm and features the signature lip at 6 o’clock. The reverse side reveals other parts of the calibre ASB19, including a series of bridges with different finishings and an openworked area with a purple background. Although the micro-rotor and equal-force barrel with its stop-work mechanism and power reserve indicator are showcased dial-side, the recessed area exposes the high-frequency (3.5Hz) balance wheel with its finger-shaped bridge and the impressive haute horlogerie finishings.

The on-trend purple colour is echoed on the light grey Nubuck leather strap with purple stitching and keepers. The strap is secured to the wrist with either a pink buckle or a folding clasp made of stainless steel.

Availability & Price

The Armin Strom Gravity Equal Force Ultimate Sapphire Purple will be limited to 25 pieces per year and retails for CHF 27,500, EUR 31,900, GBP 27,300 or USD 28,900. For more information, please consult

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