Monochrome Watches
An online magazine dedicated to fine watches

By Popular Demand, The Smaller Formex “Baby Reef” 39.5mm Automatic COSC 300M

Following the requests of its fanbase, Formex brings a smaller dive watch that is here to make big waves.

| By Denis Peshkov | 3 min read |

When released in 2020, the 42mm Formex Reef Automatic Chronometer 300M impressed enthusiasts, demonstrating a fusion of innovation and design sophistication in a highly functional tool watch. Fresh and unique, the watch offered a compelling array of features and extensive customization options. Today, just like it did with the Essence collection a few years ago, Formex unveils a more compact version of the brand’s popular diver, and we’re delighted to bring you the exciting news. Nicknamed the “Baby Reef” by the brand itself, this new 39.5mm version remains equally functional and will keep making big waves. 

Size comparison of the 42mm and 39.5mm editions of the Formex Reef dive watch

Formex, a Swiss watchmaker with a contemporary edge since its establishment in 1999, has gained recognition for crafting durable, reasonably priced tool watches infused with innovative features. The brand displays three distinctive collections and the Reef collection stands out with two models – automatic diving chronometers showcasing a solid 300m water resistance, with one featuring a GMT function.

Ad – Scroll to continue with article

The new 39.5mm Formex “Baby Reef” stainless steel case uses the same symmetrical design, with the left side mirroring the crown protection. The case is 11mm thick, slightly less than the 42mm model, with a lug-to-lug distance of 45.5mm. The unidirectional, 120-click rotating bezel, one of the most striking elements, is constructed from zirconium oxide ceramic in blue, black or green, and there’s a stainless steel option, too. The markings on the bezel ring are engraved without any colour added; only the bezel’s zero mark is filled with Super-LumiNova, yet it appears very legible. The bezel mounting system allows the wearer to swap the existing one for any other colour option without any tools, which adds to the Formex Reef’s versatility and appeal. The robust case construction and the double gasket secure crown ensure water resistance up to 300m.

The Formex Reef 39.5mm offers a choice of four dial colours – blue, silver, green, and a multi-level-lacquered white. The blue, silver, and green dials boast an iridescent, hand-applied dégradé finish, and all dials feature hand-applied, shaped and faceted indices, vertically brushed, with the angles mirror polished. The hour and minute hands get the same treatment, and with the markers, they are filled with Super-LumiNova that shines blue in the dark. The running seconds hand features a lollipop design with a luminous dot at its tip, adding a touch of visual interest. Additionally, a carefully considered date window at 6 o’clock completes the dial’s functionality.

Driving the “Baby Reef” is the self-winding, COSC-certified Sellita SW300-1 chronometer-grade movement, adorned with a custom-built skeleton rotor (even though behind a close back) and offering a substantial 56-hour power reserve.

The Formex Reef 39.5mm dive watch is available for customization, offering many possibilities with four dial options, four bezel choices, and seven bracelet and strap variations – resulting in an impressive total of 112 configurations. Noteworthy is the proprietary, gradual fine-adjustment system incorporated into all strap options (except the NATO’s pin buckle). The stainless-steel bracelet, featuring a compact folding clasp, allows for a 10mm adjustment. In comparison, the rubber and leather straps come with a carbon fibre deployant buckle offering a 7mm adjustment, allowing for convenient changes while wearing the watch.

Now available from the brand, the Formex Reef 39.5mm Automatic COSC 300M starts at EUR 1,630 with a NATO strap option, EUR 1,790 with a leather strap and EUR 1,830 with a rubber strap. On a stainless steel bracelet, it is priced at EUR 1,960. Additional ceramic or stainless-steel bezels are available for EUR 169 each. For more information or to configure your watch, visit

Leave a Reply