At the end of every issue of International Watch, we present a one-page item about a watch with a particularly handsome rear view. It’s a popular feature we’ve published for many years­– in print only and within our online full-on digital editions. 

If you’re not subscriber to our quarterly print publication, perhaps you haven’t seen this feature. If you haven’t, below we remedy that sad state of affairs with just a few of our more recent BackStory items.

Enjoy the view.

BackStory: Armin Strom Masterpiece 1 Dual Time Resonance

Even from the back of this unusual 59mm x 43.4mm oval titanium case, Armin Strom’s Masterpiece Dual Time Resonance looks like no other wristwatch. While on the front you’d see a dual-time display, a 24-hour dial and two oscillators, from the back the view underscores that four barrels power these movements. As they delightfully unwind simultaneously, they become synchronized.

As a result of this resonance, a physical phenomenon, the watch creates a highly stable timekeeping rate that heightens overall precision. Resonance, a technically difficult (and hard to regulate) technique used by only a few other watchmakers, also means the watch is more efficient and is less prone to shock-inflicted error.

Indeed, Armin Strom say that its own laboratory testing has revealed gains in precision of 15-20% for two COSC chronometer-level regulated movements placed in resonance.

Armin Strom says that its Resonant Clutch Spring (which was initially developed for an earlier watch called the Armin Strom Mirrored Force Resonance) can take up to ten minutes to synchronize the two systems. To further back its claims regarding the technology, the CSEM (Centre Suisse d’Electronique et de Microtechnique) has officially certified Armin Strom’s resonance system based on the clutch spring as being a true system in resonance.

As is evident in this back view, Armin Strom has underscored its technical proficiency with and equally impressive high level of finish on the Caliber 17 ARF bridges and plates.

The Armin Strom Masterpiece 1 Dual Time Resonance, pictured here with a titanium case, is also available with a rose gold and white gold case.  Armin Strom has also introduced the watch cased in a clear sapphire case.

The Essentials

Movement: Armin Strom manufacture calibre ARF17 with manual-winding, frequency of 3.5 Hz (25,200 vph), patented resonance clutch spring, dual off-center time indications, 4 mainspring barrels, two independent regulation systems connected by a resonance clutch spring 419 total components, power reserves: 110 hours for each movement, 

Case: 59mm x 43.4mm x 15.9mm grade 5 titanium, sapphire crystal and case back with antireflective treatment, water resistance of 50 meters
Price: $169,000 (titanium case) to $268,000 (sapphire case)

BackStory: Greubel Forsey QP à Équation

Not long ago, Greubel Forsey debuted a red gold version of its QP à Équation, an exquisite ultra-complicated timepiece with complete perpetual calendar, tourbillon and equation of time function.

The watch, which was awarded the Grand Prix d’Horlogerie de Genève award for the best Calendar in 2017, utilizes a type of ‘mechanical computer’ to manage all the changes in the displays.

This ‘computer,’ which is Greubel Forsey’s seventh ‘invention,’ is an entirely integrated twenty-five-part component composed of a stack of cams with movable fingers that shift the indications on the dial and caseback. The month’s cam changes the month (seen on the front of the dial).

But at the same time, different cams within that stack moves the Equation of Time disc, the year indicator and the seasons indication disc on the back, which is the focus of this issue’s Backstory page.

With it color-coded indicators, the Equation of Time display is the most visible of the back displays. . Essentially, the Equation of Time is the conversion factor between solar and mean time. This still rarely made complication seeks to distinguish the difference between solar time and mean time, which can vary from a few seconds to as much as sixteen minutes during the year

Greubel Forsey’s QP à Équation makes these calculations internally. The watchmaker-led construction team created an easy-to-read, color-coded display of the results on the caseback. The red portion shows when the sun is ahead of the solar mean time while the blue means the sun is behind solar mean time.

On the number scale, you see how many minutes the time is behind or ahead. The other colors show the seasons, the months are indicated using letters and two semi-circles show the equinoxes. An also-rare four-digit indicator displays the year.

And finally, if you’re wondering how all these calculations are made, feel free to watch the ‘mechanical computer’ itself, which is visible directly below a sapphire disc.

The Essentials 

Case: 43.5mm by 16mm 5N ‘Rose’ Gold

Movement: 36.4 mm by 9.6mm, 624 parts total w/86 tourbillon cage parts, flat black-polished steel tourbillon bridges, 75 olive-domed jewels in gold chatons, two coaxial series-coupled fast-rotating barrels (1 turn in 3.2 hours), 21’600 vibrations/hour, with a power reserve of 72 hours, Phillips terminal curve, Geneva-style stud, nickel silver main plates, frosted and spotted with polished beveling and countersinks, straight-grained flanks, nickel-palladium treatment, 4 engraved gold plates, 
one with the individual number, synthetic sapphire mechanical computer bridge.

Price: $695,000.