Yema Skin Diver Slim Full Lume CMM.20: Manufacture-Movement Diver With Glowing Dial, Bezel and Strap (LE 400)

Description

Yema's Skin Diver Slim Full Lume CMM.20 Limited Edition is, on paper, exactly the kind of watch the value-for-money collector hunts for: a manufacture-movement diver under USD 3,000 with 300 m water resistance, 70-hour power reserve, an in-house micro-rotor calibre, and a fully luminous dial paired with a fully luminous FKM rubber strap. At night, the entire watch — bezel, dial, strap — lights up bright blue. There's nothing else at this price point that does the same thing.

The reference (12.26.20.67.SNL.U7) is the third major iteration of Yema's Skin Diver Slim line, all built on the brand's own Calibre Manufacture Morteau (CMM.20) — the bridges and mainplates of which are made in Yema's Morteau (France) workshops, with the regulating organs sourced from Switzerland.

This is the watch in the line that fully commits to the "tool diver as art object" idea. The full-lume dial is a retro reference to 1960s diving instruments where dial paint was a single uniform luminous wash; Yema executes it on a Skin Diver case at 39mm in 316L steel, with a black sapphire bezel insert that also carries luminous markers.

Design

The case is 39mm in diameter with a 47mm lug-to-lug, and the case profile (ex-crystal) measures 9.9mm — extremely slim for a 300m diver. Total thickness with the double-domed sapphire is 12.2mm. The 316L stainless steel construction is predominantly brushed with polished bevels along the lug edges. The crown is unguarded screw-down at 3 o'clock, faithful to the vintage Skin Diver template (no crown guards, no shoulders, just the case directly meeting the lug).

The bezel is unidirectional with 120 clicks (no bezel lock — a deliberate vintage choice) and uses a black sapphire insert with a white 60-minute scale picked out in luminescent material that lights up blue at night. The bezel pip is similarly luminous.

The dial is the headline: a full-lume white dial printed with applied minute track and matte-black hour markers, sword hands with luminous fill, and a small "Yema" logo at 12. Every white area on the dial — the entire face minus the printed graphics and applied indexes — is full-lume material that emits a uniform bright-blue glow at night. The double-domed sapphire crystal sits proud over the dial, lending the watch its unmistakable old-school skin-diver profile.

The supplied strap is a luminous white FKM rubber Scales strap that lights up blue in low light. Visually, the watch in darkness is one continuous blue glowing band — case face, bezel, and strap all coordinated.

Specifications

Reference: 12.26.20.67.SNL.U7
Case size: 39mm diameter, 47mm lug-to-lug, 9.9mm case profile (ex-crystal), 12.2mm total
Case material: 316L stainless steel (brushed with polished bevels)
Crown: Unguarded screw-down at 3 o'clock
Crystal: Double-domed sapphire
Dial: Full-lume white dial (glows uniform blue in low light)
Bezel: Unidirectional dive bezel, 120 clicks, black sapphire insert with luminous 60-minute scale
Movement: Calibre Manufacture Morteau CMM.20 — automatic with bidirectional tungsten micro-rotor
Calibre dimensions: 3.7 mm thick
Balance wheel: Glucydur
Frequency: 28,800 vph (4 Hz)
Power reserve: 70 hours
Accuracy: -3 / +7 sec/day (near-COSC)
Water resistance: 300 m
Strap: Luminous white FKM rubber Scales strap (glows blue in low light)
Limited edition: 400 pieces, individually numbered
Price: USD 2,725

What's Exciting

The headline is "manufacture movement under USD 3,000". Yema's CMM.20 is one of the most affordable manufacture-grade automatic micro-rotor calibres in current production, and it's competitive on technical metrics: 70-hour power reserve (longer than the ETA 2824-2's 38 hours, longer than the Sellita SW200-1's 38 hours, longer than even the Tudor MT5601's 70 hours which costs three times more in the wider watch), Glucydur balance wheel, near-COSC accuracy. That you get a manufacture movement at all in this price range is rare; that you get it at 3.7mm thick (allowing the slim profile) is unusual.

The full-lume dial + luminous bezel insert + luminous strap combination is the other genuine differentiator. There are other full-lume dives at higher price points (Christopher Ward's C60 Lumiere, Seiko's SLA series) but the matched glowing strap is unique to Yema's execution and creates a coherent "the entire watch glows" aesthetic that the others don't fully commit to.

And at 400 pieces, this isn't a mass-production model — Yema's recent CMM.20 limited editions have been holding their value well in the secondary market, and the visual hook of the full-lume colourway means this one will be the easiest to identify in collector photographs.

History

Yema is one of France's oldest active watch brands, founded in 1948 in Besançon by Henry-Louis Belmont. The brand's most famous models are the Yachtingraf chronograph (Jacques Cousteau wore one), the Superman dive watch (issued to French Air Force pilots from 1963), and the Wristmaster dress watch line. Yema watches accompanied many French expeditions and military missions through the 1960s-1980s, and the brand's heritage as a French manufacturer (in Morteau, near the Swiss border) gives it a unique position in European watchmaking — geographically Swiss-adjacent, but culturally and operationally French.

The CMM.20 was introduced in February 2024 in the Superman Slim, Yema's first manufacture micro-rotor calibre. Designed by independent movement engineer Olivier Mory in La Chaux-de-Fonds, with regulating organs Swiss-made and bridges/mainplates manufactured by Yema in Morteau, it represented Yema's biggest investment in vertical integration in decades. The Skin Diver Slim line was launched later in 2024 as a vintage-inspired companion to the Superman Slim — drawing from Yema's 1963-onwards Skin Diver heritage. The Full Lume CMM.20 LE is the latest variant, following earlier limited-edition Skin Diver Slim CMM.20s in standard white-dial and bronze configurations. The "full lume" colourway is unique to this 400-piece edition.