I have worn and reviewed my share of Formex watches before, and, without exception, they impressed me. Whether it was the Essence or the Reef GMT, they always felt ridiculously well specced and properly built. The Reef, however, is quite a substantial watch at 42mm across. Today, Formex is releasing the downsized Reef 39.5mm Automatic Chronometer 300M. Additionally, the brand has improved the Reef’s finishing with these models. Is an almost perfect watch now finally perfect?

I got the chance to go hands-on with the new Formex Reef 39.5mm to see what’s what. Could this be the ultimate giant slayer?

Formex Reef 39.5mm blue

The new 39.5mm version (left) next to the original 42mm

The Formex Reef 39.5mm — Size matters

So, what do we have here? Simply put, it is just the Reef as we know and love it, scaled down. Whereas the original measures 42mm across, this new addition takes it to 39.5mm. It is a significant difference. Still, the 42mm version isn’t huge, and the 39.5mm model isn’t small. Both are very wearable on most wrists, but they each have a distinct character.

The 42mm size leans into the technical, modern aesthetic of the watch. At 39.5mm, somehow, that flavor feels dialed down a little bit. This may have something to do with different proportions. While the diameter has gone down, the bracelet is still 22mm wide, for instance. This means that the flared sides aren’t quite as wide, and the whole watch feels longer and more slender.

While this new Formex Reef 39.5mm is still distinctly modern and sporty, it is also more versatile. It is a little more subdued and subtle. If you want a big statement, get the 42mm Reef. If you want a flexible everyday dive watch, get the 39.5mm version. I would not worry about fit or your wrist size too much. We tried both around the office, and both fit most of us just fine. It is just a matter of what you want the watch to be. It proves that size is very much a design element that can change the character of a watch, not just the fit.

Formex Reef 39.5mm lineup

The specs of the Formex Reef 39.5mm

The Formex Reef 39.5mm may have shed 2.5mm, but it has not lost any of its impressive specifications in the process. You still get a COSC-certified Sellita SW300-1, and you still get the clever interchangeable ceramic bezels. The bracelet is still super solid and fitted with great quick-release and toolless micro-adjustment mechanisms. Oh, and it has proper screws rather than awkward pin-and-collar-connected links. And yes, a 300m water resistance rating is still paired with a sub-12mm thickness.

There are four dial colors to choose from. Three of them feature a very pronounced sunburst that completely changes color in different light. The effect is so pronounced that several colleagues assumed these were vignette dials before seeing it was actually light-play from the sunray finish. I often feel brands default to sunburst dials a bit too easily when the design doesn’t ask for it. Here, however, Formex managed to bring something characteristic and unique to the table. And if you feel it is too ornate for a dive watch, there is still a crisp white-dial alternative.

The customizability also remained from the original 42mm version. You can configure any dial with any ceramic bezel. There is a choice of the bracelet you see here or a Milanese mesh variant. Alternatively, you can opt for a very cool rubber strap with a hobnail pattern. Of course, all of these parts are available as extra options too. With everything swappable without tools, you can literally change your watch every morning.

High-definition finishing

Perhaps you read my earlier review of the Formex Reef GMT. If so, you will have learned that I was thoroughly impressed with the specs but not so much with the finishing. It wasn’t bad by any means, but it wasn’t over-performing like the rest of the watch.

I don’t know if it is because of my critical note or if it was in the works anyway, but Formex upped its game. Whereas previously, the angular, brutalist shapes were somewhat softened by the slightly hazy brushing and transitions, now we have razor-sharp finishing all around. The brushing is a little more pronounced and tactile. Furthermore, the polished chamfers are confidently cut and truly emphasize the shape of the watch.

It instantly jumped out at me when I took the new Formex Reef 39.5mm out of its box. I love that Formex took the finishing to the next level here as it makes the watch feel quite a bit more upmarket. Granted, I am very critical of and probably overly focused on this aspect of watchmaking, but I am quite sure that even if you don’t see it, you still subconsciously register the watch as being of higher quality. If I understand correctly, the new finishing level will be standard across the board for Formex.

Wearing the Formex Reef 39.5mm

The subtle changes in proportions and the resulting different character of the watch truly speak to me. I admired the Reef 42mm cognitively, but it never quite seduced me on an emotional level. This new version somehow does. I fail to find the words to properly describe what it is that makes it so different for me. As mentioned above, it isn’t that it fits me better. It has more to do with it being a little less techy in appearance. A famous maxim in music is that “writing about music is like dancing about architecture.” I feel that you can substitute music with watches in many cases. I do this for a living every single day, yet sometimes words don’t quite capture the experience.

Everything somehow seems to come together a little better on this new, smaller Reef. It is the same list of great ingredients, but they click for me now. I could see myself wearing the white-dial version with a black bezel. I think I would thoroughly enjoy that watch! As a great diver for less than €2,000, this is a very compelling option.

So, are there no complaints? Well, my earlier point about the bracelet still stands. It could do with a little more taper. I reckon an 18mm or even 20mm clasp would make it even more elegant and comfortable. Still, if you like the bold look of a non-tapering bracelet, this one is very good.

Closing thoughts

You have probably gathered by now that I think Formex has hit a home run here. What was already a very good watch is now a little more refined. The smaller footprint and finer finishing make a significant difference.

I am repeating myself, but the difference isn’t so much a matter of size. Rather, it is a matter of proportions. The 42mm version feels more brutal and sporty. The Reef 39.5mm feels more versatile and refined. I would encourage you, if interested, to consider choosing between the two in this vein. Both are likely to fit you just fine if your wrist is in the 16–19cm range, but they exude a different kind of style.

With the finishing now at the same level as the feature set, the Formex Reef has become a potential giant slayer. With the same price as the 42mm version, starting at €1,830, I cannot think of other dive watches that offer a similarly impressive package. As I have said before, you shouldn’t buy watches for their spec lists but, rather, for how they make you feel. And that is a good thing for most brands out there. Otherwise, this would possibly be the only surviving diver in this segment. The new Formex Reef 39.5mm is available via the Formex website now.

Watch specifications

Reef 39.5mm Automatic Chronometer 300M
Blue sunburst, green sunburst, silver sunburst, or white with applied luminous indices and date window
Case Material
Stainless steel with ceramic bezel insert
Case Dimensions
39.5mm (diameter) × 11.4mm (thickness)
Case Back
Stainless steel, screw-in
Sellita SW300-1 — chronometer-certified caliber, automatic and hand winding, 28,800vph frequency, 56-hour power reserve, 25 jewels
Water Resistance
Choice of stainless steel three-row bracelet, stainless steel Milanese mesh bracelet, or hobnail-pattern rubber strap (22mm width)
Time (hours, minute, central seconds), date, 60-minute dive bezel
Starting at €1,830