Yema’s Skin Diver Slim Bronze CMM.20 promises patina and in-house movement performance
Jason LeeYema is one of the more interesting French names to revisit right now, because its story isn’t built around dress-watch mythology so much as purpose-built instruments. Founded in 1948 by Henry‑Louis Belmont (a top graduate of the National Watchmaking School of Besançon), the brand grew up in the post‑war era with a reputation for pragmatic manufacturing and sport‑watch intent — the sort of company that has long framed its watches around diving, sailing, motorsport and even space exploration.
That tool-watch identity also has some unusually specific calling cards. In 1967, Yema filed a patent for the bezel‑lock mechanism on its Superman dive watch — an early, safety-minded solution aimed at preventing accidental bezel movement underwater. And decades later, Yema claims a place in European space-watch lore: in 1982, French astronaut Jean‑Loup Chrétien wore a Yema Spationaute I, which the brand describes as the first Western European watch sent into space. Whether you’re deep in the weeds on provenance or simply like a good backstory, the point is that Yema’s best-known watches have historically been designed to do something, not just look the part.
All of which makes the brand’s latest release feel less like nostalgia-for-nostalgia’s sake, and more like Yema returning to a familiar brief. The Skin Diver Slim Bronze CMM.20 is pitched as a modern take on the brand’s 1960s skin divers, but with a very contemporary hook: a manufacture micro‑rotor CMM.20 designed to keep the case notably slim, while still aiming at proper dive-watch credentials — and it arrives in a 39mm bronze case. That combination is worth pausing on. “Skin diver” as a category tends to lean into compact proportions and a certain easy-wearing simplicity; a micro‑rotor is one of the more direct ways to chase thinness without giving up automatic winding, and it’s a detail you don’t see everywhere at this level.
The case
The bronze case is 39mm in diameter, 10mm thick, and 47mm lug-to-lug, with 20mm curved lugs that should help it sit down rather than perch. The finishing is described as largely brushed, with polished bevels adding a bit of definition along the edges. There’s also an unguarded crown – no locking device here.
Yema points out how the case will develop patina through air, moisture, and everyday wear until it becomes something personal. Bronze can look warm and nautical when it’s fresh, then gradually darken and spot, sometimes dramatically, depending on how you live with it. It’s not for everyone, but it does suit a watch that’s already trading on the romance of 1960s dive gear. The reassuring part is that, alongside the character-building material choice, this is still positioned as a serious water watch with 300m water resistance, backed up by a screw-down crown.
A lot of the character also comes from the bezel and dial choices. The unidirectional rotating bezel is described as entirely sapphire, and Yema calls the effect “faded ghost,” as if it’s already lived a life.
The dial
Available in either green or grey (the latter being a 200-piece limited edition), the dial itself is where Yema doubles down on legibility in a way that feels deliberately bold. The layout pairs oversized applied triangular hour markers with Arabic numerals, and those markers extend toward the centre so the dial doesn’t feel sparse, even at 39mm. The handset keeps the tool-watch vocabulary intact: an arrow-style minute hand for quick reading, a long pencil-style hour hand, and a lollipop seconds hand for an easy “it’s running” check. The brand notes that the markers and hands are outlined in gilt finish and filled with Super‑LumiNova. Underneath that, the base is described as an enamel dial base with a dark grey matte surface.
The movement
Through the sapphire exhibition caseback sits the Calibre Manufacture Morteau 20, or CMM.20, a manufacture micro‑rotor movement that Yema clearly wants you to see. According to Yema, the calibre was designed in Switzerland, developed in France by Yema’s watchmakers, with bridges and mainplates manufactured in Yema’s Morteau workshops.
Micro‑rotors have a particular appeal even for people who don’t normally care about casebacks: the architecture can look cleaner and more intentional than a full rotor blanketing the movement, and here it’s also doing functional work. Yema states the movement’s architecture allows a thickness of 3.70mm, which is the sort of figure that helps explain how you land at a 10mm dive watch rather than something meaningfully chunkier. The performance claims are also framed as part of the pitch. Yema quotes a 70-hour power reserve, credited to a tungsten micro‑rotor and a large barrel, and states an accuracy range of -3/+7 seconds, described as near chronometer-level performance.
The strap
The finishing touch is appropriately utilitarian: an FKM rubber strap intended to match the dial colour, with honeycomb motifs extending right to the end of the strap. Aesthetically, it helps balance the warmth of bronze with a more contemporary, muted tone.
The verdict
For collectors who like the idea of a watch that changes with them, the Skin Diver Slim Bronze CMM.20 makes a neat case: vintage skin diver proportions and cues up front, a modern micro‑rotor movement at the centre, and a bronze case that will look increasingly like it’s been somewhere after a year or two on the wrist.
Yema Skin Diver Slim Bronze CMM.20 pricing and availability
The new Yema Skin Diver Slim Bronze is available now from Yema’s e-boutique and its retailers. The grey dial model is a limited edition of 200 pieces, while the green dial is a standard production model. Price: €2,249
| Brand | Yema |
| Model | Skin Diver Slim Bronze |
| Reference | 12.26.20.34.ZN.U4 (green) 12.26.20.39.ZNL.U9 (grey) |
| Case Dimensions | 39mm (D) x 10mm (T) x 47mm (L2L) |
| Case Material | Bronze, sapphire bezel insert |
| Water Resistance | 300 meters, screw-down crown |
| Crystal(s) | Sapphire front and back |
| Dial | Green or faded grey |
| Strap | FKM rubber, bronze pin buckle |
| Movement | CMM.20, in-house, automatic |
| Power Reserve | 70 hours |
| Functions | Hours, minutes, seconds, undirectional diving bezel |
| Availability | Now, grey dial model limited to 200 pieces |
| Price | €2,249 |