Formex REEF 39.5 Review: A Swiss Dive Watch That Does It All
- October 24, 2025
A Microbrand Powerhouse With 300M of Swiss-Made Confidence
Formex has built a strong reputation in the world of independent watchmaking, delivering precision, comfort, and Swiss craftsmanship across its lineup. Whether it’s the Essence ThirtyNine for those who appreciate chronometer-certified elegance or the Field Automatic for adventure seekers, the brand offers something for every enthusiast.
Now, Formex takes on the dive watch segment with the REEF 39.5 Automatic COSC 300M Silver, a robust yet refined timepiece that balances performance and versatility. But does it hold its own against the competition?
A Case Built for Adventure
One of the REEF 39.5’s biggest strengths is its perfectly proportioned case. At 39.5mm in diameter and just 11mm thick, it maintains a compact, wearable profile while still offering a robust 300M water resistance. Unlike many divers that feel overly bulky, this one wears comfortably on a variety of wrist sizes.
The brushed and polished stainless steel case exudes premium finishing, and thanks to its scratch-resistant ceramic bezel, durability is top-notch. The 120-click unidirectional bezel moves with a satisfying precision that rivals much pricier dive watches.
For those who prefer a larger case, Formex also offers the REEF in 42mm, as well as a REEF GMT version for travelers who need a dual-time function.
Dial & Legibility: Pure Elegance Underwater
The silver dial on this model is nothing short of stunning. With a vertical brushed texture, it plays beautifully with light, shifting from a crisp metallic sheen to a warmer tone depending on the angle. Applied indices and BGW9 Super-LumiNova ensure excellent legibility, even in the depths of the ocean or just a dark movie theater.
The date window at 6 o’clock is subtle and well-integrated, keeping the dial symmetrical and uncluttered. Whether on land or underwater, the REEF 39.5 is as easy to read as it is to admire.
COSC-Certified Precision
At the heart of the REEF 39.5 beats the Sellita SW300-1, a Swiss automatic movement that’s COSC-certified for chronometer-grade accuracy. Operating at 28,800 vibrations per hour (4Hz) with a 56-hour power reserve, it offers both precision and longevity, qualities every dive watch should have.
Bracelet & Comfort: A Cut Above the Rest
One of Formex’s most underrated strengths is its commitment to comfort. The stainless steel bracelet features the brand’s patented micro-adjustment clasp, allowing for quick and easy size adjustments on the fly. Whether your wrist swells on a hot day or you’re layering over a wetsuit, the perfect fit is always within reach.
Additionally, the quick-release system lets you swap between the rubber strap and steel bracelet in seconds, no tools required (and yes, this truly is a HUGE benefit).
Why the Formex REEF 39.5 Stands Out
- Compact Yet Capable: A true dive watch with 300M water resistance that remains slim and wearable.
- Exceptional Swiss Precision: COSC-certified movement ensures chronometer-level accuracy.
- Premium Build Quality: Scratch-resistant ceramic bezel, sapphire crystal, and high-end finishing.
- Versatile Design: Rugged enough for the ocean, refined enough for a suit.
- Comfort-Driven Engineering: Micro-adjustable bracelet and quick-release straps enhance daily wear.
For those who want a dive watch that blends technical prowess with everyday elegance, the Formex REEF 39.5 is a serious contender
Final Thoughts
The Formex REEF 39.5 Automatic isn’t just another dive watch, it’s an independent Swiss timepiece built to the highest standards. Whether you opt for the smaller 39.5mm version, the larger 42mm model, or the REEF GMT, you’re getting cutting-edge materials, precision engineering, and a design that transitions effortlessly from sea to city.
For those already impressed by the Essence ThirtyNine but looking for a sportier alternative, the REEF 39.5 is the perfect next step in the Formex lineup.
Specifications:
Brand – Formex
Model – REEF 39.5 Automatic
Case Material – Stainless Steel
Case Dimensions – 39.5mm x 11mm
Water Resistance – 300M (30ATM)
Strap – Stainless steel bracelet with micro-adjustment, rubber and leather strap option
Crystal – Sapphire
Bezel – Ceramic, 120-click unidirectional
Movement – Sellita SW300-1 (COSC-certified)
Power Reserve – 56 hours
Lume – Yes (BGW9 Super-LumiNova)
Limited Edition – No
Price – Approx. €2,070* (depends on configuration)
Official store link here.
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About Formex: Key Questions Answered
Is Formex a luxury watch brand?
Formex is a premium Swiss watchmaker that blends luxury craftsmanship with modern innovation. Known for its COSC-certified movements, tool-free case systems, and high-grade materials like titanium and carbon fiber, Formex delivers luxury quality at a more accessible price point.
What makes the Formex Reef 39.5 mm special?
The Formex Reef 39.5 mm stands out for its compact size, 300 m water resistance, and COSC-certified Swiss movement. Its interchangeable bezel and strap system allows easy customization, making it both a serious dive watch and an everyday luxury piece.
Does the Formex Reef 39.5 mm have a certified chronometer movement?
Yes. The Reef 39.5 mm is powered by a Sellita SW300-1 automatic movement that is COSC-certified for precision, ensuring exceptional accuracy and reliability under demanding conditions.
Can you swap straps and bezels on the Formex Reef 39.5 mm without tools?
Absolutely. The Reef 39.5 mm features Formex’s patented tool-free system, allowing quick changes between straps, bracelets, and bezels. It’s designed for versatility, letting owners adapt the watch to any style or occasion in seconds.
