Greubel Forsey GF09XV Balancier Convexe S2 Review

First unveiled in 2019, Gruebel Forsey’s Convexe design showcases the brand’s efforts to move toward bolder, more architectural designs while staying true to its heritage. The signature feature of the Convexe design is the double-curved case, praised since its debut for its instantly recognizable looks and ergonomic comfort. 

The unique curvature allows a few things to happen: First, the caseback hugs the wrist for maximum comfort, and second, it allows for some interesting play under the dial with architecture and negative space. As the dial nears the six o’clock position it plunges down towards the wrist, leaving ample space under the crystal, which is used to display the balance wheel at a bizarre and awesome 30° angle. The result is meant to evoke a cityscape with bridges, elevations, and vanishing lines. 

In 2023, Greubel Forsey introduced the Balancier Convexe S² in titanium, the smallest-ever diameter within the Convexe collection at 41.5 mm. The Balancier Convexe S² movement is hand-wound and comprised of 301 parts, plus a 68-part escapement platform. The power comes from two coaxial, series-coupled fast-rotating barrels, delivering 72 hours of power reserve. At its heart is that signature 30° inclined balance wheel, an in-house patented variable-inertia design tilted at that angle to counter gravity and improve timekeeping accuracy, that beats at 21,600 vibrations per hour. The architecture is built around a multi-level, openworked bridge that puts the brand’s technical performance and hand-finishing standards in the spotlight. 

In true Greubel Forsey fashion, this isn't just a shrinking of a preexisting watch, it’s a refinement of a modern classic. And proof that very big ideas can come in very small packages.