Introduced at Watches and Wonders Geneva 2025, the G.F.J. Calibre 135 marked a new era in the history of Zenith by fulyl re-engineering Calibre 135, the most decorated movement in the history of observatory chronometry trials. That inaugural piece came in platinum with a lapis lazuli dial, now at Watches and Wonders Geneva 2026, Zenith presented the G.F.J. Calibre 135 Yellow Gold and Bloodstone Dial we brought you a couple of weeks ago, along with this Tantalum and Onyx Dial piece.
Cased in one of our all-time favorite materials, tantalum—highly mastered by Audemars Piguet in the late 1980s and early 1990s—, the new G.F.J. Caliber 135 Tantalum Onyx Dial ref. 98.1865.0135/21.C212 is a very interesting-looking watch and one that we were not expecting at all. Tantalum is twice as dense as stainless steel and almost as dense as gold—16.4 grams/cubic centimeter vs. 19.3 grams/cubic centimeter for gold. It is a very hard-to-machine metal with a distinctive blue-grayish luster; therefore, this new watch deserves further consideration.
Things to Know About the Watch
The case geometry is unchanged from last year's platinum debut and this year’s yellow gold watch with 39 mm in diameter and just 10.5 mm thick, with a stepped bezel and curved lugs drawn from the 1950s dress watch vocabulary. What differs is everything, from material to palette. The tantalum case with its glue-grayish luster seems to be the perfect canvas for the deep black onyx dial.
The three-part dial retains the brick guilloché chapter ring that references the facade of Zenith's Le Locle manufacture, but the center is now onyx, a deep black, lustrous stone. The small-seconds subdial at 6 o'clock remains in black mother-of-pearl, and the indexes are diamonds. Production is capped at 161 pieces, matching Zenith's age in 2026.
The Movement
The G.F.J is powered by and updated version of the iconic manual wound calibre 135. This 157-part movement beating at a frequency 18,000 vph provides a power reserve of 72 hours. This time, the movement is not decorated the same way as in the G.F.J. Platinum 160th-anniversary piece, but with Côtes de Genève.
This manual wound movement deliberately beats at a slower rate as it was engineered in the original 1940s calibre to maximize rate stability for observatory competition. The re-engineered version retains this architecture while adding a 72-hour power reserve, hacking seconds, spring-mounted shock jewels, and a Breguet overcoil hairspring. COSC certification is held to ±2 seconds per day. The oversized 14 mm balance wheel and characteristically offset center wheel remain the movement's defining structural statements.
On the Wrist & Price
The Zenith G.F.J. in tantalum is a convincing argument for the material’s high density and unique luster in serious horology. Due to its size and design, it wears as a proper dress watch, slim enough for a shirt cuff, but heavy on the wrist. The onyx dial is the real visual event with its deep, black, profound look. Three straps are included—gray-bluish nubuck alligator, gray calfskin, and black alligator, all equipped with tantalum pin buckles.
Sticker Price USD 83,400. More info on Zenith here.
