Jacques Bianchi Marseille is back with another collaboration involving former US Navy diver Brock Stevens, and this time, the focus is on combat diving. The new JB300 Professional builds on the pair’s previous release with a forged carbon case, a COSC-certified movement, and a handful of details developed around feedback from active military divers. I think there’s quite a bit here that deserves a closer look, especially if you’re into modern dive watches with a more specialized design.
Stevens reportedly consulted divers from the Navy SEALs, MARSOC, and Army Special Forces during development. Some of that feedback came from personnel using the MK 25 rebreather, where underwater operations can stretch across several hours. Weight was apparently one of the bigger concerns, which helps explain the decision to move away from the stainless steel construction of the previous model.
The JB300 Professional uses a forged carbon case with a Grade 5 titanium inner core. There’s also a black DLC-coated titanium bezel and reinforced fixed lugs, similar to what we’ve seen on Tudor’s Pelagos FXD. At 41.5mm wide and 13mm thick, the dimensions seem reasonable for a watch with this kind of intended use. I’d be curious to see how the carbon construction affects the overall weight and wearing experience, particularly during longer periods on the wrist.
Visually, I think Jacques Bianchi got quite a bit right here. The matte black dial features oversized luminous markers, broad hands, and a clean layout without a date window. There’s very little competing for your attention, and the left-sided crown carries over from the previous collaboration. To me, the overall design feels coherent, even with the more aggressive styling.
The bezel is probably my favorite detail. Its fully graduated scale uses two different lume colors, with the first 15 minutes glowing green and the remaining markings glowing blue. According to Stevens, the distinction helps combat divers track shorter navigation intervals underwater. It’s a small detail, but I appreciate the reasoning behind it. I’d also be interested in seeing how easily those colors can be distinguished in actual diving conditions.
Inside, the Swiss-made Soprod P024 automatic movement now carries COSC chronometer certification, with an accuracy specification of -4 to +6 seconds per day. That’s a welcome upgrade over the previous JB300, although I think the case construction and dial execution are doing more to define this particular release. The watch also includes a sapphire crystal and 300 meters of water resistance.
The $1,950 price seems… okay to me, given the materials and movement certification. Still, that’s a competitive part of the dive watch market, and buyers will have plenty of alternatives to consider. The fixed lugs also mean you’re limited to pass-through straps, which could be a sticking point for anyone who enjoys changing between straps and bracelets.
Production is limited to 500 pieces, with 200 reserved for the brand’s Unit Watch Program and 300 allocated for public sale.
My take is that the JB300 Professional has a lot going for it on paper. I like that the design choices have identifiable reasons behind them, and the military connection makes sense within Jacques Bianchi’s history. I’d still want to spend time with one before drawing conclusions about comfort or durability. For now, the details are enough to keep me interested.
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Michael Peñate is an American writer, photographer, and podcaster based in Seattle, Washington. His work typically focuses on the passage of time and the tools we use to connect with that very journey. From aviation to music and travel, his interests span a multitude of disciplines that often intersect with the world of watches – and the obsessive culture behind collecting them.