Monochrome Watches
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SIHH 2019

Armin Strom Dual Time Resonance Sapphire – Total Transparency on the Dual Movement

Armin Strom's concept watch with two independent movements in resonance fully exposed to the world.

| By Brice Goulard | 5 min read |

Armin Strom is on fire. After its first watch equipped with two oscillators connected by a resonance clutch spring – the revolutionary Mirrored Force Resonance – the brand unveiled an impressive development based on this concept, a dual time watch with two movements – the Masterpiece 1 Dual Time Resonance. And having got a taste for the impressive mechanics of this watch, Armin Strom decided it would be a shame to hide the show inside a metallic case. This is why, for SIHH 2019, Armin Strom introduces a sapphire version of Dual Time Resonance, fully exposing its movements to the world.


Two oscillating bodies in close proximity influence each other and eventually synchronize. This odd phenomenon was first reported in 1665 by Christiaan Huygens, the Dutch scientist, mathematician, astronomer and inventor. Ill and bedridden, Huygens noticed that two of his recently invented pendulum clocks were oscillating in sympathy. If the synchronization was disturbed by some interference, it would, he observed, reestablish itself in a short period of time.

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The coupling clutch used to enhance the effect of resonance.

The application of this phenomenon, known as resonance, has not been widely embraced by watchmakers. Two centuries ago, Astide Janvier and Abraham Louis Breguet adapted the system to create “Pendules Sympathiques”. More recently, watchmakers in search of greater accuracy and stability have sought to take advantage of the synchronicity of oscillators in wristwatches – for instance, François-Paul Journe, Beat Haldimann or Antoine Preziuso.

Armin Strom Mirrored Force Resonance Guilloche Dials by Voutilainen

In 2016, Armin Strom presented one of the most spectacular applications of the phenomenon with its Mirrored Force Resonance. The crucial factor behind the synchronization of Huygens’ pendulums was their coupling, hung as they were on the same wooden bar and subject to its vibrations. Similarly, Armin Strom’s Claude Greisler connected twin oscillators by a steel spring attached to their stud. The two balance wheels get coupled thanks to the tiny vibrations of the spring.

Application on a Dual Time watch

Following the introduction of the concept in 2016 (and several iterations in the following months), Armin Strom unveiled its first watch regulated by resonant oscillators and equipped with a complication – a dual time indication.

Powering the Armin Strom Masterpiece 1 Dual Time Resonance is the hand-wound calibre AFR17 with its spectacular architecture consisting of two movements built on the same mainplate. Each one has its own barrel, gear train and regulator to display an independent time zone. The time for each movement is adjusted via a dedicated crown.

Armin Strom Masterpiece 1 Dual Time Resonance

These highly practical and independent displays adapt to all types of time zones, including rare ones, which vary by a half hour or a quarter of an hour. It can also be used as a timer or countdown mechanism. For each of the time displays, there is a dedicated 24h day/night indication (in the centre at 6 o’clock – the hand matching the colour of the hour markers on their respective sub-dials) and a dedicated power reserve indication.

The spectacular part comes from the movement’s architecture. The twin movements are interdependent. With their prominent position at 12 o’clock, their oscillators are connected by the clutch spring to enhance resonance and beat in unison. The four barrels (two for each movement) are all wound by the same crown to ensure they are wound simultaneously. This architecture ensures that the same energy is delivered by the barrels to their associated oscillator and avoid any disturbance to the phenomenon of resonance. For each movement, the power reserve – a robust 110 hours when fully wound – is indicated via a roller acting as a feeler spindle on a cone moving up and down. The cool power reserve mechanisms are visible on each side of the movement at the back of the watch.

The new Armin Strom Dual Time Resonance Sapphire

With such impressive mechanics, it would be rather sad to hide them in a metallic case. The Armin Strom Dual Time Resonance Sapphire, with its fully transparent sapphire case,  ensures a transparent view of the movement. Technically identical to the first iteration, sized equally too – meaning a hefty 59mm x 43.4mm (including lugs) x 13mm – the new sapphire version differs in the choice of case material and dial colours.

In order to give full exposure to the movement, the case is crafted from solid blocks of sapphire, which are notoriously difficult to work with. “Diamond-coated tools spend days cutting, then milling the case components from massive sapphire crystal blocks. These are then left for a few days to allow any tension generated by the heat of machining to be evenly distributed throughout the crystal. The case is then polished for days, transforming the opaque milled crystal into one that is crystal clear,” explains the brand. And given the extreme hardness of sapphire crystal, a lot of breakage can be expected during the milling stage.

The beauty of having a sapphire crystal case is, of course, to have an uncluttered view of the movement… but then again, this comes with several challenges. The complete transparency of the case doesn’t allow for shortcuts in the finishing of the movement. Every single part, every side of the movement, every face of a component has to be decorated in order to produce a pleasant result.

In addition to the new case material, the Armin Strom Dual Time Resonance Sapphire also introduces new dial colours. A clever choice, the two sub-dials (one for each time zone) are now picked out in different shades of blue, making it easier to consult the time. The dials are still hand-guilloché with a refined pattern. Complementing the look is a blue alligator strap with a steel folding buckle.

The Armin Strom Masterpiece 1 Dual Time Resonance Sapphire will be a limited edition of 8 pieces. Price is set at CHF 280,000 –  compared to CHF 180,000 for the titanium edition. More details during the SIHH 2019 and on

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