Beyond its commemorative dimension, the collection serves as a platform for exploring the full spectrum of technical refinement, extending chronometric precision into the realm of rare, high-end and inherently exacting materials. In this new execution, the disciplined architecture of the Calibre 135 is housed within tantalum, a metal whose density and resistance demand absolute control in fabrication, turning material constraint into a defining element of the watch’s character.
Tantalum is defined by its density and its restraint. Its natural blue-grey hue carries a subdued luminosity, neither reflective nor matte, but deeply metallic. Exceptionally resistant to corrosion and highly biocompatible, it is also notoriously difficult to machine. Its hardness and weight require specialised tools, slow tolerances and meticulous finishing.
Tantalum stands among the most demanding metals used in modern watchmaking. Exceptionally hard and dense, it resists machining and challenges finishing at every stage. Its behaviour under the tool differs fundamentally from that of gold or platinum, requiring slower fabrication, specialised handling and absolute control to achieve comparable refinement. The 39.5mm case preserves the stepped bezel and sculptural lugs characteristic of the G.F.J., yet in tantalum its character shifts. Compact, weighty and deliberate, it lends the chronometer a quiet intensity — precision rendered in a metal rarely mastered at this level of execution.
The dial continues this study in depth and discipline. A central disc in black onyx introduces a polished, almost liquid surface. At 6 o’clock, the oversized small seconds counter appears in grey mother-of-pearl, adding subtle tonal variation without disrupting the monochrome composition. Encircling the dial, the brick-pattern guilloché sector, inspired by the façade of the ZENITH Manufacture, structures the periphery. Eleven baguette-cut diamond indexes punctuate the dial with architectural precision. The interplay of linear diamond indexes and slender white gold hands creates a composition defined by restraint, where each element contributes to balance and proportion.
At its core beats the Calibre 135, developed in the late 1940s specifically for observatory chronometry competitions. Its competition version, the 135-O, secured 235 chronometry prizes, including five consecutive first prizes at the Neuchâtel Observatory between 1950 and 1954, a record that remains unmatched.
Re-engineered for the 21st century, the calibre retains its 13-ligne diameter and 2.5 Hz frequency while incorporating modern technical refinements. It delivers 72 hours of power reserve. The oversized balance wheel features regulation screws, a Breguet overcoil and the characteristic double arrow-shaped regulator for fine adjustment. A stop-second mechanism ensures precise time setting. Each movement is regulated to +/- 2 seconds per day and officially certified by the COSC.
Through the sapphire caseback, the calibre reveals Cote de Genève, hand-chamfered bridges and a dark ruthenium finish whose depth echoes the tone of the tantalum case, reinforcing the watch’s measured and architectural character.
Released in a limited edition of 20 pieces, the G.F.J is available for pre-order exclusively from the brand’s physical and online boutiques, as well as through authorized retailers worldwide.
