The revival of mid-century aquatic timepieces has been a dominant theme in the horological landscape for the better part of a decade, yet few manufacturers possess the legitimate historical archive to back up their vintage-inspired releases. YEMA stands as a notable exception, maintaining a lineage that traces directly back to the golden era of recreational diving. With the release of the Skin Diver Slim Bronze CMM.20, the French watchmaker is not merely reissuing a cosmetic update of a 1960s aesthetic; they are fundamentally re-engineering the proposition of what a skin diver can be. This release marries the warm, evolving character of a bronze case with a sophisticated, proprietary micro-rotor movement, signaling a shift towards higher technical independence and a revitalization of the Morteau watchmaking ecosystem.
The term "skin diver" evokes a specific era and utility. Unlike the bulky, over-engineered professional saturation divers of the 1960s, skin divers were crafted for the enthusiast—the recreational free-diver who needed equipment that was functional underwater but ergonomic enough for daily wear. This new bronze iteration captures that dual-purpose spirit perfectly. The case measures a restrained 39mm in diameter, a sweet spot that acknowledges modern preferences while respecting vintage proportions. What truly sets this housing apart, however, is the use of bronze. This alloy is dynamic, reacting to the wearer's environment, humidity, and skin chemistry to develop a patina that is entirely unique to each owner. Over time, the bright, metallic gold tone will darken and mature, giving the watch a rugged, lived-in appearance that feels organic rather than manufactured.
Courtesy of YEMA
The profile of the case is remarkably slender for a mechanical dive watch, clocking in at just 10mm thick. This slimness is a critical attribute of the skin diver genre, distinguishing it from the slab-sided divers that often dominate the category. The geometry features curved lugs with a 20mm width, extending to a lug-to-lug distance of 47mm. This ensures the watch hugs the wrist rather than sitting atop it. The finishing on the bronze is a thoughtful mix of brushed surfaces and polished bevels, creating a play of light that highlights the architectural lines of the case before the patina eventually softens the contrast. The absence of crown guards is another deliberate nod to the 1960s, leaving the screw-down crown exposed and easily accessible, embossed with the YEMA logo.
While the exterior pays homage to the past, the interior is decidedly forward-thinking. The engine powering these timepieces is the Calibre Manufacture Morteau 20 (CMM.20), a movement that represents a significant industrial achievement for YEMA. Developing a proprietary caliber is a complex undertaking, but creating a micro-rotor movement requires an even higher level of engineering finesse. The CMM.20 is ultra-thin, measuring just 3.70mm in height, which directly enables the watch's slender 10mm case profile. By integrating the rotor into the plane of the movement rather than sitting it on top, the architects of this caliber have saved crucial vertical millimeters without sacrificing performance.
The micro-rotor itself is fashioned from a high-density tungsten alloy. This material choice is functional rather than merely decorative; because the rotor is smaller than a standard central oscillating weight, it needs to be heavier to generate sufficient kinetic energy. Tungsten’s density ensures that the bi-directional winding mass winds the mainspring efficiently, securing a substantial power reserve of 70 hours. This means the watch can be taken off on Friday evening and will still be running on Monday morning, a practical convenience for collectors who rotate their timepieces. The movement operates at a frequency of 4Hz (28,800 vibrations per hour) and boasts an accuracy rating of -3 to +7 seconds per day, skirting the edges of chronometric performance standards.
The visual presentation of the CMM.20 is revealed through a sapphire exhibition caseback, a feature often omitted on dive watches to ensure water resistance. Here, YEMA has managed to maintain a 30 BAR (300 meters) depth rating while still allowing a view of the mechanics. The movement bridges and mainplates are manufactured in YEMA's Morteau workshops, treated with a galvanic finish that gives the movement a modern, technical appearance. The architecture is distinct, with the small tungsten rotor spinning alongside a Glucydur balance wheel. This balance wheel is non-magnetic and resistant to thermal expansion, ensuring stability across varying temperatures. The entire assembly speaks to a broader initiative by the brand to insource production and rely on a local network of suppliers within the French-Swiss Jura arc.
Courtesy of YEMA
The dial layout serves as the primary interface for the wearer, and on the Skin Diver Slim Bronze, it is an exercise in legibility and retro typography. The design utilizes a "sandwich" style effect with oversized applied markers. The hour indices are a mix of distinct triangles and Arabic numerals at the cardinal points, a configuration that offers instant orientation. The hands are equally bold; the minute hand is a large arrow shape, critical for tracking dive times, while the hour hand is a prolonged pencil style. The seconds are tracked by a lollipop hand, a classic diver trope. All these elements are finished in a gilt tone that complements the bronze case warmness, creating a cohesive color palette that feels intentionally aged yet sharp.
Two distinct variations of this model are available, each offering a different character through their colorways and bezel treatments. The first variant features a dark green enamel dial with a slightly grained matte finish. This texture absorbs light rather than reflecting it, which enhances the legibility of the gilt markers and the white Super-LumiNova filling. The bezel on this model is crafted from sapphire, mimicking the glossy look of vintage Bakelite inserts but with the scratch resistance of modern material. The green of the bezel insert matches the dial, creating a seamless visual flow from the center to the edge. The use of Grade A C1 Super-LumiNova ensures that the watch glows brightly in low-light conditions, a non-negotiable feature for a professional diver.
The second variation is the Limited Edition Grey model, which introduces a "Faded Ghost" aesthetic. This version is restricted to just 200 numbered pieces, adding a layer of collectibility. The dial here is a matte dark grey, paired with a sapphire bezel that has been treated to look like a vintage component that has spent decades in the sun. This "ghost" grey bezel gives the watch a monochromatic, stealthy appearance that contrasts beautifully with the warm bronze case. The luminescence on this model is a lime-colored vintage-inspired Super-LumiNova, differing from the white tone of the green model, further leaning into the heritage look. The serial number and limited edition count are engraved on the caseback, marking its place in the production run.
Courtesy of YEMA
Both models come mounted on a specially designed FKM VITON rubber strap. This is not a standard off-the-shelf rubber strap but one engineered for durability and comfort. FKM rubber is known for its resistance to dust, chemicals, and UV light, meaning it won't degrade or attract lint like cheaper silicone alternatives. The surface of the strap features a "Scales" pattern, a geometric relief that adds depth and texture. This design choice serves a dual purpose: it visually breaks up the flatness of the rubber, giving it a more technical tool-watch vibe, and it improves grip. The strap is secured with a bronze buckle that matches the case finish, ensuring that the patina will develop uniformly across the entire wrist presentation.
The manufacturing story behind these watches is central to their value proposition. The CMM.20 caliber is the result of a collaboration with Olivier Mory and is produced in the Morteau region, the historical cradle of French watchmaking. YEMA has invested heavily in modernizing their production lines and workshops to bring this level of manufacturing in-house. The components are sourced from partners within a tight 72-kilometer radius spanning the French-Swiss border. This regional ecosystem, recognized by UNESCO as Intangible Cultural Heritage, allows for a level of quality control and reactivity that is difficult to achieve with far-flung supply chains. The bridges and plates are machined in France, the regulating organs come from Switzerland, and the final assembly and regulation happen in Morteau.
On the wrist, the 39mm bronze case offers a presence that is distinct from steel. Bronze warms to body temperature quickly and has a tactile quality that feels substantial. The combination of the compact lug-to-lug distance and the supple FKM strap makes for a very comfortable wearing experience. It slides easily under a shirt cuff thanks to the 10mm thickness, yet the unique color of the metal and the complexity of the dial ensure it doesn't disappear. It straddles the line between a robust tool watch and a conversation piece. The lack of crown guards and the vintage-style sapphire crystal, which is double domed to 2.20mm, contribute to a silhouette that feels authentically mid-century.
The water resistance of 300 meters is achieved despite the exhibition caseback, a testament to the precision of the case machining and seals. The Incabloc double cone shock resistance system protects the movement from impacts, making the watch suitable for active use. Whether used for actual diving or simply for surface swimming and daily wear, the specifications are over-engineered for most civilian applications. The unidirectional rotating bezel features a 0-60 scale with a luminescent pip at 12 o'clock, allowing for the timing of events with precision. The sapphire insert on the bezel is particularly noteworthy as it provides a depth and luster that ceramic or aluminum cannot replicate, recalling the depth of vintage acrylic bezels without the fragility.
Courtesy of YEMA
The dial's readability is enhanced by the generous application of Super-LumiNova. On the Green model, the white lume offers a crisp contrast during the day and a strong glow at night. On the Grey Limited Edition, the lime-colored lume provides a softer, aged look in daylight that transitions to a functional glow in the dark. The "sandblasted" texture of the enamel dial reduces glare, ensuring that the hands are always the focal point. The gilt finishing on the hands and markers is not just a color choice but a nod to the galvanic gilding processes used in the past, adding a touch of warmth that ties the dial to the bronze case.
The choice of bronze for a skin diver is particularly appropriate given the material's nautical history. Historically used for ship fittings, propellers, and deep-sea diving helmets due to its resistance to saltwater corrosion, bronze belongs in the ocean. As the watch builds its patina, it effectively records the life of its owner. A watch worn frequently in the ocean will develop a green verdigris, while one worn in a dry climate might darken to a rich chocolate brown. This interactive element makes the ownership experience dynamic; the watch you buy today will look different a year from now.
YEMA's decision to equip this model with a micro-rotor movement is a bold statement of intent. Micro-rotors are typically found in high-horology pieces from prestigious Swiss houses, often commanding significantly higher price points. By democratizing this architecture, YEMA is offering enthusiasts a rare mechanical treat. The unobstructed view of the movement gear train, usually hidden by a central rotor, allows the owner to appreciate the finishing and layout of the CMM.20. The 190 components that make up the movement are assembled with a focus on durability and precision, bridging the gap between industrial reliability and artisanal flair.
The strategic direction of YEMA with the CMM.20 line suggests a future where French watchmaking reclaims some of the territory lost during the Quartz Crisis. By focusing on "Manufacture" status—designing, machining, and assembling locally—they are rebuilding the industrial fabric of Morteau. The Skin Diver Slim Bronze is a product of this renaissance. It is not just a retro-styled accessory but a proof of concept for the region's manufacturing capabilities. The 72-kilometer supply chain is a model of sustainability and regional cooperation, reducing the carbon footprint associated with production while supporting local craftsmanship.
Courtesy of YEMA
In terms of competition, the Skin Diver Slim Bronze occupies a unique niche. There are many bronze divers on the market, and many vintage reissues, but few combine a sub-10mm profile, a proprietary micro-rotor movement, and a sub-$3,000 price point. The combination of the high-tech internal mechanics with the raw, evolving exterior material creates a juxtaposition that is highly appealing. It satisfies the desire for something mechanically interesting while fulfilling the craving for a tool watch that looks like it has stories to tell.
Availability for these timepieces is structured to cater to both collectors and general enthusiasts. The Skin Diver Slim Bronze CMM.20 is priced at $2,490.00. The Grey model is strictly limited to 200 numbered timepieces, making it a target for those who value exclusivity and the specific "ghost" aesthetic. The Green model, while sharing the same technical specifications and price, offers a more classic nautical look with its deep emerald tones. Both versions represent a compelling value proposition considering the inclusion of a manufacture micro-rotor caliber and the high quality of the case and strap materials. As YEMA continues to push upmarket with its technical offerings, these bronze skin divers stand as a solid entry point into their new era of French manufacture horology.
Case: Bronze material, 39mm diameter, 10mm thickness, 47mm lug-to-lug, 20mm lug width. Brushed finishes with polished bevels. Unidirectional diving bezel with sapphire insert (Green or "Faded Ghost"). 2.20mm double domed sapphire crystal. Sapphire exhibition case-back. Screw-down crown with embossed YEMA logo. Water resistance 30 BAR / 300m.
Movement: Calibre Manufacture Morteau 20 (CMM.20) micro-rotor automatic. 3.70mm thickness. Tungsten micro-rotor, Glucydur balance wheel, Incabloc double cone shock resistance. 28,800 A/h (4Hz) frequency. 70-hour power reserve. Accuracy -3/+7 seconds per day. 33 jewels, 190 components. Galvanic decoration.
Dial: Sandblasted enamel with matte finish (Dark Grey or Dark Green). Applied hour markers and hands in gilt finish. Grade A Super-LumiNova (Lime-coloured for Grey, White C1 for Green). Triangular markers with Arabic numerals.
Strap: FKM VITON® rubber "Scales" strap in matching dial color (Grey or Green). Bronze buckle with brushed finish.
Price: $2,490.00
Reference Number: 12.26.20.39.ZNL.U9 (Grey Limited Edition), 12.26.20.34.ZN.U4 (Green)
Notes: Grey model limited to 200 numbered timepieces. Movement designed by Olivier Mory and manufactured in France and Switzerland within a 72km radius. Bronze case will develop a unique patina over time.