For decades, the name Yema has evoked images of high-seas adventure, aviation precision, and unforgiving environments. Founded in 1948 by Henry-Louis Belmont in the watchmaking heartland of Morteau, France, the brand carved out a formidable reputation as a master of ultra-reliable, purpose-built tool watches. Enthusiasts worldwide revere milestones like the 1963 Yema Superman—a heavy-duty instrument designed to withstand the crushing pressures demanded by professional deep-sea divers—and the Flygraf chronograph, built to endure the rigorous spatial and temporal calculations required by pilots.
Yet, the contemporary trajectory of Yema, under the stewardship of Ambre France since 2009, tells a story of ambitious reinvention. While maintaining a firm grip on its legendary utilitarian heritage, the brand has embarked on a calculated mission to reclaim the pinnacle of French mechanical watchmaking. This renaissance has materialized through proprietary engineering, most notably the development of the ultra-slim CMM.20 calibre featuring a micro-rotor.
Having successfully injected this in-house architecture into integrated sports watches like the Wristmaster, the brand’s rugged dive icons (the Superman and Navygraf), and the cushion-shaped Granvelle dress collection, Yema is breaking new ground. The latest chapter in this horological evolution introduces the brand’s first-ever moon phase watch: the dressier, elegantly proportioned Senans collection, spearheaded by the stunning Senans Grande Lune.
Chronology of a Renaissance: From Morteau to the Micro-Rotor
To understand the significance of the Senans Grande Lune, one must trace the deliberate steps Yema has taken over the past decade and a half to transform from a vintage-revival brand into a true vertically integrated manufacture.
The Ambre France Era and the Quest for Independence (2009–2021)
When Ambre France acquired Yema in 2009, the immediate objective was to stabilize the brand, honor its rich archival catalog, and reconnect with collectors through faithful re-editions. However, leadership harbored grander ambitions. True independence in the Swiss-dominated horological landscape required genuine in-house manufacturing capabilities, particularly in "France Horlogerie."
The CMM.20 Breakthrough (2022)
The turning point arrived in 2022 with the introduction of the Calibre Manufacture Morteau (CMM.20). Developed in close collaboration with renowned French movement designer and watchmaker Olivier Mory, the CMM.20 was engineered to be a state-of-the-art micro-rotor movement measuring just 3.7mm in thickness while boasting a robust 70-hour power reserve. This foundation allowed Yema to escape the constraints of off-the-shelf movements and enter the realm of ultra-thin, high-performance watchmaking.
Expanding the Portfolio (2022–2025)
The micro-rotor movement quickly became the beating heart of Yema’s upscale strategy. It debuted in the integrated-bracelet Wristmaster, before trickling down into the brand’s core tool watch lines—giving rise to the slenderized Superman and Navygraf models. Seeking to prove that its engineering prowess extended far beyond rugged sports environments, Yema subsequently introduced the cushion-cased Granvelle collection, signaling a pivot toward classical dress watch aesthetics.
The Apex: Arrival of the CMM.22 and the Senans Collection (Late 2026)
Culminating this multi-year development cycle, Yema has now unveiled the Senans collection. By evolving the CMM.20 into the new CMM.22 calibre—integrating a complex, proprietary moon phase complication without compromising the movement’s svelte profile—Yema has officially bridged its historical tool-watch DNA with sophisticated, classical dress watchmaking.
Supporting Data: Anatomy of the Senans Grande Lune
The Yema Senans Grande Lune is a masterclass in proportion, historical homage, and mechanical ingenuity. Every element of the watch has been meticulously specified to compete directly with established luxury houses while maintaining an aggressive value proposition.
Case Architecture and Ergonomics
Breaking away from the cushion-shaped geometry of the Granvelle, the Senans Grande Lune adopts a classical round silhouette. The design is a direct nod to vintage Calatrava-style dress watches from the golden age of mid-century watchmaking (the 1940s and 1950s).
- Dimensions: The watch measures 38.5mm in diameter, striking the absolute "sweet spot" for contemporary dress watch tastes—large enough to command wrist presence, yet compact enough to slide effortlessly under a bespoke shirt cuff.
- Thickness: At an impressively slim 8.7mm (excluding the double-domed sapphire crystal), it fulfills all the technical requirements of a true ultra-thin dress watch.
- Lug-to-Lug: Measuring 46.4mm, the case hugs the wrist comfortably.
- Finishing: The case features a stepped, mirror-polished bezel that plays brilliantly with ambient light. This is contrasted by vertically brushed case flanks and gently curved lugs designed to follow the natural contours of the arm. Water-resistance is rated at a practical 50 meters.
The Dial: A Tribute to Architectural Heritage
The collection takes its evocative name from the Royal Saltworks of Arc-et-Senans, an 18th-century architectural masterpiece near Morteau designed by visionary architect Claude-Nicolas Ledoux. Famed for its distinctive semicircular geometry, the saltworks’ architectural layout directly inspired the large, asymmetrical aperture for the Grande Lune positioned at 7 o’clock.
The dial is anchored by a traditional barleycorn guilloché-like stamped pattern at its center. Framing this central texture is a circular-brushed chapter ring featuring applied baton-style indices and a raised peripheral minute track. Yema offers the Senans Grande Lune in three distinct, highly compelling colorways:
- Golden Dial: Warm, vintage-inspired, and immensely sophisticated.
- Blue Dial: A deep, classic hue that catches the light dynamically.
- Black Dial: Dramatic, formal, and strikingly modern.
To tie the aesthetic together, the hour markers, hands, and the inner framing ring of the central dial are treated with Grade X Super-LumiNova, ensuring nocturnal legibility.
The CMM.22 Movement: Engineering the Moon Phase
Integrating a moon phase complication into an ultra-thin automatic movement is a notoriously difficult engineering challenge. The added mass and spatial requirements of a traditional 3D lunar display typically bloat a movement’s thickness.
Working once again with Olivier Mory, Yema solved this by building upon the CMM.20 micro-rotor architecture. The resulting Calibre CMM.22 adds a mere 1mm of height, bringing the total movement thickness to a remarkable 4.7mm.
What sets the Senans’ moon phase apart is its unconventional execution. Rather than utilizing a traditional rotating disc behind a window, the moon itself is a stationary, solid block of Super-LumiNova crafted with hyper-realistic lunar topography. To animate the passing lunar cycles (waxing and waning), Yema engineered an ultra-thin rotating mechanical bilobe that sweeps gracefully over the luminous orb like a celestial shadow.
Operating at a modern frequency of 28,800 vibrations per hour (4Hz) and delivering an exceptional 70-hour power reserve via a tungsten micro-rotor mounted on ball bearings, the CMM.22 is a visual treat. Through the sapphire display caseback, admirers can view contemporary charcoal-grey electroplated bridges, which create a striking industrial contrast against polished screw heads and purple jewel bearings.
Official Responses and Brand Vision
The launch of the Senans collection has generated significant buzz across the horological community, prompting reflections from Yema’s leadership regarding the brand’s strategic evolution.
In official statements accompanying the release, Yema’s executive team emphasized that the brand refuses to be pigeonholed as a single-genre manufacturer. While the Superman, Navygraf, and Flygraf will forever remain foundational pillars of the company’s identity, the mastery achieved through the CMM movement family demands broader horizons.
"Our mission with Ambre France has always been clear: to reclaim the heritage and sovereignty of French mechanical watchmaking," a Yema brand representative noted. "Creating a robust tool watch is an achievement of durability. Creating an ultra-thin, in-house micro-rotor dress watch with a novel mechanical moon phase complication is an achievement of artistic and technical maturity. With the Senans Grande Lune, we are proving that French manufacture watchmaking can rival the finest ateliers in the world, while remaining accessible to true enthusiasts."
Olivier Mory, the movement architect behind the CMM.20 and CMM.22, highlighted the unique technical hurdles overcome during the development process: "Designing a micro-rotor movement leaves very little margin for error regarding space. Adding a complex complication like an animated mechanical bilobe for the moon phase—especially one featuring a massive, heavy 3D luminescent sculpture—required rethinking energy transmission without sacrificing the 70-hour power reserve or the 4Hz frequency. We achieved something genuinely unique here."
Implications for the Watchmaking Industry
The introduction of the Yema Senans Grande Lune carries several profound implications for both the brand and the broader independent watchmaking market.
1. Elevating the "Made in France" Narrative
For decades, high-end mechanical watchmaking dialogue has been dominated by Swiss, German, and occasionally Japanese manufacturers. By designing, developing, and assembling proprietary high-complication movements (like the CMM.22) directly in Morteau, Yema is spearheading a modern renaissance for French horology. The Senans collection proves that French industrial watchmaking can produce sophisticated dress pieces that stand shoulder-to-shoulder with established Swiss competitors.
2. Redefining Value in Independent Watchmaking
Each of the three colorways of the Senans Grande Lune is strictly limited to 200 pieces, ensuring a degree of exclusivity that appeals to collectors. Despite this limited production run, high-end micro-rotor architecture, and intricate mechanical complications, Yema has priced the collection remarkably aggressively:
- EUR 2,470 when paired with a refined leather strap.
- EUR 2,570 when paired with a classic steel mesh bracelet.
In a market where micro-rotor watches with in-house manufacture movements routinely command five-figure sums from Swiss luxury houses, Yema’s pricing strategy poses a formidable challenge to competitors, offering unmatched mechanical and aesthetic value per euro spent.
3. A Complete Brand Transformation
Ultimately, the Senans collection signifies that Yema is no longer merely a "heritage revival" brand coasting on the laurels of its 20th-century dive watches. It is a fully fledged, forward-looking manufacture capable of traversing the entire spectrum of watchmaking—from deep-sea tool watches to elegant, high-complication dress pieces. For collectors who have watched Yema’s upward trajectory over the past five years, the Senans Grande Lune is not just a surprise; it is the logical, triumphant next step in a remarkable horological journey.
