Independent watchmaker Armin Strom has upgraded its flagship complication with a precious stone dial. The Mirrored Force Resonance Ruby is a five-piece limited edition with a dial cut from natural ruby.

Initial thoughts

Armin Strom is arguably the second-most prominent watchmaker (after F.P. Journe) to successfully bring “resonance” watches to market. We extensively covered the subject of coupled oscillator watches recently, which examines Armin Strom’s unique approach to achieving this mysterious effect. 

Within this narrow niche, Armin Strom’s Mirrored Force series is certainly the broadest collection of resonance watches on the market, with multiple movements and many variations exploiting the almost magic coupling between two sprung balances.

This new limited edition employs the familiar in-house caliber ARF21, which connects the two hairspring by a long, swivelling blade spring — dubbed the Resonance Clutch Spring. While the movement is certainly well known, this particular iteration of the watch is quite surprising: a thin slice of natural ruby serves as the dial, with all the imperfections and liveliness of a natural mineral. 

Using a ruby dial is not only aesthetically appealing but poetic for a mechanical watch. The jewels serving as bearings inside every movement are synthetic rubies — a fancy sort of industrial mineral glass. The uneven bright pink and violet shades of the Mirrored Force Resonance Ruby’s dial assure us there is nothing artificial or synthetic about this lively stone.

While stone dials have a rich history, this is a first for Armin Strom — using a raw gem in such a manner. The brand has built its reputation on modern-looking mechanics, with an emphasis on technical watchmaking, and has dabbled in engine-turned dials in recent years, so this venture into more esoteric territory is most welcome.

Really, real ruby

As impressive as the mechanics inside the Mirrored Force Resonance Ruby are, this limited edition’s point is to showcase the precious ruby dials. As typical for the Mirrored Force Resonance collection, the dial is off-centred, oriented towards the three o’clock position. 

Since each natural ruby cut has its own inclusions, each piece will, on some level, be unique. Depending on the light, the gem carries many beautiful shades, from milky pink to sharper red hues. The mineral has discernible vines and lattices denoting its crystaline structure, making for a seemingly rough and uneven texture hiding behind the hands.

While stone dials are usually polished to an even, flawless finish, this ruby dial embraces and plays on its own imperfections, blending sterile precision mechanics with natural roughness. 

The two mirrored sub dials for the seconds are also painted in a matching magenta hue, which complements the natural ruby sheen well. All the indices are painted white, which along with the sharply polished hands make for good legibility.  

Since this remains firmly a Mirrored Force Resonance watch, the dial is heavily open-worked, fully revealing the two sprung balances and much of the movement’s main plate. The open architecture works especially well here, allowing us to better appreciate the richness of the natural ruby against the dull, uniform gleam of the synthetic jewels within the movement itself.

The stainless steel case measures a substantial 43 mm in diameter and is indistinguishable from other Mirrored Force Resonance variants from Armin Strom. The round case profile is simple and features angular lugs that break sharply from the case band. The pusher at two o’clock syncs the seconds hands, while the polished tab at six o’clock is a quirky motif of the brand. 

A synchronised movement

Not quite concealed behind the ruby dial ticks the Armin Strom cal. ARF21, a movement that essentially carries two calibres on the same mainplate, conjoined only through their oscillators. Though we have broadly covered the subject of “resonance” watches in the past, including Armin Strom’s elastic connection specifically, a simplified explanation of the two coupled oscillators is necessary.

In short, the two sprung balances are joined through their hairsprings’ pinning points by an auxiliary spring, which forces them to fall into an out-of-phase synchronicity. 

The end result of this elaborate setup is, at least in theory, more stable timekeeping. What’s not theoretical is the unmistakable look — seeing the two balances beat together is surely a curious sight. As for the stable timekeeping, the cal. ARF21 features two independent barrels, which are not connected in any way, save for the winding works (which do not affect their discharge into the going train). 

It appears than only one gear train is in fact linked to the cannon pinion and hour wheel, meaning that one that gear train directly drives the hour and minutes hands on the ruby dial, while the other only serves as a feedback loop to help keep the rate stable. 

The cal. ARF21 also comes with the requisite flyback seconds hands, engaged by the pusher at two o’clock, to allow the user to synchronise the mirrored sub-seconds hands and witness the “resonance” effect take hold. The two free-sprung balances beat at 3.5 Hz (akin to Omega’s current series of Co-Axial calibers) and the movement holds a comfortable power reserve of about 48 hours. 

A degree of high-end industrial finishing is applied to all visible components, which, combined with the hypnotic dance of the Resonance Clutch Spring, makes for a very compelling tableau. Curiously, some hidden components, like the plate covering the motion works, are left in a rough state.

This is presumably an aesthetic choice, perhaps to create contrast with the finished surfaces, since each Armin Strom movement is assembled twice in the brand’s Bienne manufacture, and the rest of the movement is finished quite well.

Key facts and price

Armin Strom Mirrored Force Resonance Ruby
Ref. ST23-RF.10

Case diameter: 43 mm
Height: 11.55 mm
Crystal: Sapphire
Material: Stainless steel
Water resistance: 30 m

Movement: Cal. ARF21
Features: Hours, minutes, double seconds, elastically-coupled oscillators
Frequency: 25,200 beats per hour (3.5 Hz)
Winding: Manual
Power reserve: 48 hours

Strap: Alcantara strap with stainless steel pin buckle

Limited edition: Yes, 5 pieces
Availability: From Armin Strom retailers
Price: CHF85,000 excluding taxes

For more, visit Arminstrom.com.