To mark its 160th anniversary this year, Zenith unveiled the Zenith G.F.J. Calibre 135, named after founder Georges-Favre Jacot and housing a modern, technically upgraded version of the historic Calibre 135. Seeing it on the second day of Watches & Wonders, during one of my earliest appointments, I hadn’t quite shaken off the travel haze and was unsure what to make of the buffing files and gentian wood laid out on the side of the presentation table, but as soon as I saw the watch, everything snapped into focus. That it came in a platinum case with stepped lugs, that the dial was utterly striking, that the recreation of this legendary movement had come with upgrades including a stop-seconds, a longer power reserve and a slightly larger balance, and that this level of finishing showed up in the halls of Palexpo, it was all unexpectedly captivating.

Zenith G.F.J (Image: Revolution©)

The Calibre 135 was produced between 1949 and 1962, with a total of 11,000 examples made during that period. It was produced in two versions: one for commercial use, and the other, the 135-O, developed specifically for observatory competitions. The 135-O amassed an extraordinary 235 chronometry prizes over its production run, including five consecutive first prizes at the Neuchâtel Observatory from 1950 to 1954, one of the most impressive winning streaks in watchmaking history.

In 2022, 10 vintage 135-O movements were restored, hand-finished, and cased as a 10-piece limited edition in collaboration with Kari Voutilainen and Phillips. Now, the movement has been rebuilt with subtle but meaningful technical upgrades in a 160-piece limited edition.

When More is More

Whereas the case and dial of the Kari Voutilainen x Phillips limited edition launched in 2022 were modest and understated, befitting the ascetic single-mindedness of the Caliber 135-O, the G.F.J. is unmistakably luxurious. It retains the same horological substance but presents it with far greater visual richness.

Unmistakably luxurious, the dial consists of three parts: an engraved chapter ring, a lapis lazuli central disc and blue mother-of-pearl small seconds sub-dial (Image: Revolution©)

The G.F.J. has a 39mm platinum case that measures 10.5mm in height. It is slightly larger than the 2022 limited edition as it’s an entirely different case, with elegant, stepped lugs and bezel. It wears compact on the wrist due to its 45.75mm lug-to-lug measurement.

The case has been sensitively finished, with brushing on the flanks and a highly polished bezel and upper lug facets. The transitions between brushed and polished areas are crisp. The crown is also polished, with a stamped “G.F.J.” signature.

The hands and indexes are faceted, polished white gold, and in person, their sharp surfaces catch the light beautifully against the mix of textures (Image: Revolution©)

The dial of the Zenith G.F.J. Calibre 135 is extremely elaborate, striking from afar and equally rewarding up close. It comprises three parts: an engraved chapter ring, a lapis lazuli primary disc, and a small seconds insert in lush blue mother-of-pearl. The chapter ring is CNC engraved with a brick pattern, in a nod to the brick façade of the Zenith watch manufacture in Le Locle. It is punctuated by white gold indexes that are faceted and diamond-polished, along with 40 white gold beads. These gleaming surfaces bring the textured dial to life. The lapis lazuli disc, with its deep celestial hue and natural flecks of pyrite, adds a sense of grandeur, while the iridescent small seconds in blue mother-of-pearl offers a soft contrast in both colour and texture. The combination of polish, engraving, stone, and iridescence come together in a composition that is unapologetically vivid yet harmonious.

(Image: Revolution©)

It is paired with a dark blue alligator strap but there’s also the option of a full platinum bracelet with centre links engraved with the same brick pattern found on the chapter ring. The bracelet version comes at a significant premium, nearly doubling the price.

The New & Improved Zenith Calibre 135

The Calibre 135 in the G.F.J was built from the ground up with improved specs; everything from the mainspring to the train wheels and balance have been reworked while retaining the same architecture and 13-ligne diameter.

A masterpiece in the hard-fought race for precision, now upgraded with a longer power reserve, optimised tooth profiles, a larger balance, hacking seconds, and decoration executed to the highest standard. (Image: Revolution©)

The fundamental construction of the Calibre 135 was conceived by watchmaker Ephrem Jobin, who was tasked by Zenith’s technical director at the time, Charles Ziegler, to develop a chronometer-grade movement capable of competing in the observatories of Neuchâtel, Geneva, Kew Teddington, or Besançon. From the outset, the movement had a strong foundation, and add to that the exceptional skill of elite régleurs like René Gygax and Charles Fleck, who regulated and adjusted the movement, its inherent potential could be fully exploited.

Zenith Watch advertisement from 1954, featuring René Gygax

Its architecture featured an off-centred gear train, a deliberate choice to free up space for an unusually large balance wheel beating at 18,000 vibrations per hour. Instead of occupying the middle of the movement, the centre wheel is positioned to the left and drives both the third wheel and a central pinion. This layout was intended to maximise room for the balance. Still, one might reasonably wonder how much space is gained, since a centrally positioned centre wheel can still accommodate a fairly large balance given that they sit on different planes. Kari Voutilainen’s Calibre 28, for example, demonstrates that a conventional layout can also make room for a generously sized balance.

However, by relocating the centre wheel, the size of the central axle and its pinion can be reduced quite significantly, enabling the balance to be approximately 1 to 1.2mm larger, which is a meaningful gain when marginal advantages can prove decisive in observatory trials. At the same time, the bridge of the escape wheel is lowered, with the balance overlapping it.

To accommodate an oversized balance, the centre wheel is located next to the crown wheel, driving both the third wheel and a central pinion (Image: Revolution©)

While not officially stated in the announcement, the balance wheel in the new Zenith G.F.J. Calibre 135 is slightly larger than the original, which already measured 14mm. The resulting inertia is nine times that of the balance in the El Primero. The power reserve has also been extended from 40 to 72 hours. This improvement was achieved by reducing the size of the barrel arbour and introducing a new mainspring made from Générale Ressorts’ Bioflex, a modern, high-performance alloy known for its enhanced elasticity and superior fatigue resistance. The tooth profiles of the train wheels have also been optimised to improve transmission efficiency. Lastly, the inclusion of a stop-seconds mechanism completes a movement built around precision.

The massive screw balance has been fitted with a Breguet overcoil hairspring and retains the double index regulator found on the original Calibre 135-O movement. Like its predecessor, the new movement is highly precise, with a maximum deviation of ±2 seconds per day, certified by the COSC.

A shock absorber has now been installed around the balance pivot to protect it from impact. (Image: Revolution©)

It is satisfying to see a movement originally conceived to triumph in some of the most demanding competitions in watchmaking history now endowed with a level of finishing that matches its mechanical excellence. The bridges are decorated with the same brickwork motif found on the dial and finished with rounded anglage. Countersinks for the jewels and screws are present, and the shape of the bridges has been subtly reworked to introduce sharp inner angles.

Rounded anglage and sharp internal angles are both present. (Image: Revolution©)

(Image: Revolution©)

At CHF 48,900, the price is compelling for everything it offers – a platinum case, a highly elaborate three-part stone dial, and an upgraded movement finished to a high standard. In fact, it costs significantly less than any comparably finished time-only watch from an independent watchmaker, many of whom, after all, develop their approach to chronometry in the tradition of observatory-grade timekeeping. The G.F.J. connects directly to a chapter in horological history when precision was king, and the Calibre 135 was built expressly to meet the demands at the very edge of what was mechanically possible.

Tech Specs: Zenith G.F.J. Calibre 135

Reference: Ref. 40.1865.0135/51.C200
Movement: Manual-winding Calibre 135; 72-hour power reserve
Functions: Hours and minutes; small seconds
Case: 39.15mm × 10.5mm; platinum; 50m water resistance
Dial: Lapis lazuli; mother-of-pearl (small second counter); Blue bricks guilloché on the outer ring
Strap: Dark blue alligator leather strap with platinum pin buckle; additional black calfskin leather and blue “Saffiano” calfskin leather. Optional for purchase: platinum bracelet with double folding clasp
Availability: Limited edition of 160 units
Price: CHF 48,900 CHF / EU 52,900 Euros / USD 49,900