I’m sure the obvious has already been stated, the Serica 5303 refresh comes with the respectable COSC certification, ensuring that each chronometer has a unique COSC engraved number on the movement, and has gone through a battery of tests while maintaining consistent accuracy performance. But in addition to the COSC certification, Serica is also making sure that the movement is up to snuff by performing its own in-house testing. From here on out, any watch provided by Serica will also come with their Grand Chronomètre credential, which assures the buyer that once the watch is fully assembled, it will then undergo additional accuracy, power reserve and shock resistance testing.

To the eye, the exterior of the Serica 5303 COSC diver remains entirely the same (well, almost). Once again, Serica’s calling card of design consistency is on full-display. The dial continues to use their peculiar hour marker arrangement – Super-Luminova C3 filled rectangular bars at the cardinal hours and lollipop markers that extend towards the center of the dial. Like all the models in the Serica catalog, a broad minute and hour handset dances around the dial (also filled with Super-Luminova C3). The only subtle difference is that the S617 word-marking is no longer displayed and is replaced by the Chronomètre tag. For those who are curious, the S617 name refers to a retired French submarine called the e téméraire (the brave one). Although the S617 moniker no longer remains as part of the 5303 name, the watch still remains as Serica’s distinct flagship diver, and continues to pay tribute to their vintage military inspiration.

One of my favorite features of any Serica piece is the ability to choose the crown placement of your liking, whether that be at three o’clock, or if you’re feeling zesty (or you’re an actual lefty), elect to go with a crown at nine o’clock. The case lines are highlighted by varying uses of finishes and hits all the sweet spots in regards to proportions – 39mm in width, 46.5mm in lug to lug and 12.2mm in thickness. The MVP of the entire package however just so happens to be their steel mesh bracelet. The Serica 5303 COSC retains the 20mm solid end-link design that houses an additional articulating link, which then transitions into a silky smooth steel mesh bracelet that tapers to 16mm at the clasp.