Formex Reef 39.5mm Automatic COSC 300M Forged Carbon

I am a fan of Formex. I like that the brand attempts to create the best-built watch within its chosen price category. The designs aren’t for everyone, but the build quality is undoubtedly excellent. I’ve had hands-on experience with Formex’s Field and Reef models. On both counts, they left me impressed, particularly given their asking prices, so it’s nice to cover the brand’s latest release. Formex recently launched its more compact 39.5mm version of the Reef with forged carbon components, and it’s quite a looker! Let’s dive in.

The Formex Reef 39.5mm Automatic COSC 300M Forged Carbon

On paper, the Reef 39.5mm Automatic COSC 300M Forged Carbon is familiar territory. The “Baby Reef” platform is already well established — a compact, highly wearable 39.5mm dive watch with a 300m depth rating, a chronometer-certified automatic movement, and one of the most practical interchangeable bezel systems on the market.

It’s a watch built on logic, usability, adaptability, and durability. But this version feels different. After all, forged carbon is a statement. The dial and bezel insert are made of this material, providing the distinct, marbled visual texture many watch enthusiasts love. Each dial and bezel insert is formed under pressure, resulting in an unpredictable pattern that ensures no two pieces are ever quite the same.

While most dials aim for perfection, this one embraces imperfection, controlled, deliberate, and deeply visual. Even through a screen, it has presence. The interplay of light across that fractured carbon surface gives the watch a sense of depth that flat dials simply can’t replicate. If you have seen a Doxa Sub 300 in carbon, you will know what I mean. The texture seems to shift, move, and feel almost organic. And paired with the Reef’s clean, functional layout, bold markers, and generous lume, it creates a contrast that is hard to ignore.

Familiar details 

Formex hasn’t altered the fundamentals. The 39.5 × 45.5 × 11mm steel case remains slim for a 300m-rated dive watch, offering proportions that have already proven themselves in everyday wear. Inside beats the Sellita SW300-1, chronometer-certified, reliable, and entirely appropriate movement for a watch that positions itself as a serious tool rather than a showcase piece. With that, we get a 56-hour autonomy, which is no slouch in this era of longer power reserves.

It would have been easy to lean too far into the aesthetic and let the forged carbon dominate the narrative. Instead, Formex keeps the core premise of the Reef intact. The quick-release bezel system is still there, and the strap and bracelet interchangeability remains. The functionality hasn’t been sacrificed at the altar of design. If anything, the design has enhanced it.

Concluding details 

From where I’m sitting, this is a watch that seems to straddle two worlds. On one hand, it’s still very much a modern dive watch, capable, robust, and thoughtfully engineered. On the other hand, it introduces an element of individuality that’s sometimes missing in this segment. Of course, the real test will come later, on the wrist, in changing light, over time.

As far as first impressions from afar go, the Formex Reef 39.5mm Automatic COSC 300M Forged Carbon doesn’t feel like a minor variation. It feels like a shift in tone and a reminder that even within the constraints of a tool watch, there’s room for expression. Bravo, Formex.

The Reef 39.5mm Automatic COSC 300M Forged Carbon starts at €1,960 / US$2,085 / £1,820 on a leather, nylon, or rubber strap and €2,070 / US$2,230 / £1,990 on a stainless steel mesh or three-row bracelet. For those who want to take advantage of bezel interchangeability, additional bezels with plain steel or black, blue, or green ceramic inserts are also available for €160 / US$180 / £130. The initial batch of this watch is limited to 100 pieces, available for pre-order now. Formex expects shipping to begin in early May 2026. Let me know what you think of this new version of the Reef in the comments below!

Watch specifications