Greubel Forsey stands as a beacon of contemporary haute horlogerie, renowned for its technical inventiveness and uncompromising finishing. Since its founding, the brand has consistently challenged the boundaries of watchmaking, introducing complex mechanisms and architectural designs that have become benchmarks within the industry. The GMT Balancier Convexe continues this tradition, presenting a reimagined approach to the GMT complication, now in a form that reflects both technical mastery and refined ergonomics.
Architectural mechanics
At the heart of the GMT Balancier Convexe lies a dial that orchestrates a multitude of indications in a harmonious amphitheatre layout. The central feature is the terrestrial globe, crafted from titanium, which rotates once every 24 hours in sync with the Earth’s natural motion. This globe, positioned at the core of the dial, serves as both a visual anchor and a functional display, encircled by a 24-hour chapter ring that differentiates day and night with distinct black and white segments. The continents are rendered in relief, offering a tactile dimension to the timekeeping experience.
Surrounding the globe, the amphitheatre hour ring carries engraved and lacquered minute markers, while the hours and minutes are indicated by hands with red triangles filled with Super-LumiNova for enhanced legibility. The second time zone (GMT) is displayed on a subdial, and a small seconds indicator is positioned nearby, executed in polished blued steel. The power reserve, now seamlessly integrated into the dial, offers a clear indication of the 72-hour autonomy provided by the twin fast-rotating barrels.
The movement itself is a showcase of Greubel Forsey‘s technical mastery. Comprising 496 components, it features the brand’s signature 30° inclined balance wheel, suspended beneath a flat black polished steel bridge and supported by polished steel pillars. This configuration is designed to optimize chronometric performance by reducing positional errors due to gravity. The balance wheel, with six gold mean-time screws and a Phillips terminal curve on the balance spring, operates at a frequency of 21,600 vibrations per hour. The movement is entirely hand-finished, with frosted and polished surfaces, beveled edges, and olived-domed jewels set in gold chatons, underscoring the artisanal dedication of the Greubel Forsey atelier.
On the reverse, a sapphire disc engraved with 24 cities provides a universal time display, including a subtle nod to the brand’s heritage by replacing Paris with La Chaux-de-Fonds, the home of Greubel Forsey. This disc also accounts for summer and winter time, enhancing the practicality of the world time function.
The Convexe case – designed for wearability
The case of the GMT Balancier Convexe is sculpted from titanium, chosen for its lightness and durability. The convex architecture, a signature of the collection, is designed to follow the natural curvature of the wrist, improving both comfort and visual impact. The caseband measures 42.90 mm, while the bezel extends to 44.90 mm, and the overall height, including the domed sapphire crystal, reaches 17.60 mm. The three-dimensional, variable geometry-shaped bezel is hand-polished and features straight graining, while the lugs are profiled and secured with screws for structural integrity.
Water resistance is rated at 5 ATM (50 meters), and the crown, also in titanium, is finished with a combination of polishing, frosting, and straight graining, bearing the GF logo. The caseback is fitted with a high domed sapphire crystal, offering an unobstructed view of the movement and the universal time disc. The strap options include a hand-sewn textured rubber or a titanium bracelet with a folding clasp, both integrating seamlessly with the case design.
Continues innovation
The Greubel Forsey GMT Balancier Convexe exemplifies the brand’s dedication to mechanical innovation and aesthetic refinement. By centering the terrestrial globe within a meticulously engineered amphitheatre, the watch offers a comprehensive and intuitive display of multiple time zones, all within a case that prioritizes both ergonomics and visual depth. Limited to just 22 pieces, this timepiece stands as a testament to the art of invention and the pursuit of horological excellence.
Greubel Forsey GMT Balancier Convexe Technical Specifications
In titanium – Limited edition
Patented hand-wound movement
GMT • 2nd time zone • rotating globe with universal time and day-and-night • universal time on 24 time zones • summer and winter time • cities observing summer time • GMT pusher • 30° inclined Greubel Forsey balance wheel system • hours and minutes • small seconds • power-reserve
Movement
MOVEMENT DIMENSIONS
Overall diameter: 37.80mm
Thickness: 13.80mm
NUMBER OF PARTS
Movement: 496 parts
Escapement platform: 59 parts
NUMBER OF JEWELS
72
Olived-domed jewels in gold chatons
CHRONOMETRIC POWER RESERVE
72 hours
BARRELS
Two series-coupled fast-rotating barrels (1 turn in 3.2 hours), one of which is equipped with a slipping spring to avoid excess tension
BALANCE WHEEL
In-house variable-inertia with 6 gold mean-time screws (12.60mm diameter)
FREQUENCY
21’600 vibrations/hour
BALANCE SPRING
Phillips terminal curve
Geneva-style stud
BRIDGES AND MAIN PLATES
Titanium and nickel-silver
Frosted, polished bevelling and countersinks, straight-grained flanks
ESCAPEMENT PLATFORM
Inclined at a 30° angle
Flat black polished steel, polished bevelling and countersinks, straight-grained flanks
Polished steel pillars
Flat black polished and barrel polished steel balance wheel bridge
GEARING
Involute circle profile
Inclined gear with profiled teeth on fourth wheel
DISPLAYS
Hours and minutes
Small seconds
2nd time zone GMT
Rotating globe with universal time
Day-and-night
24 time zones universal time
Summer time, winter time
72-hours power reserve on a sector
Exterior
CASE
Titanium with curved sapphire crystal
Three-dimensional, variable geometry-shaped bezel, hand-polished with hand-finished straight graining
Profiled lugs, screwed fixing
Transparent back with curved and high domed synthetic sapphire crystal
Engraved GMT pusher
Titanium security screws
Raised engraving “GMT” and “Greubel Forsey”
CASE DIMENSIONS
Caseband diameter: 42.90mm
Bezel diameter: 44.90mm
Case height: 15.10mm
Height on synthetic sapphire crystals: 17.60mm
WATER RESISTANCE OF THE CASE
Water-resistant 5atm – 50m – 164ft (standard NIHS 92-20/SN ISO 22810:2010)
CROWN
Titanium, polished, frosted and straight-grained, with GF logo
DIAL SIDE
Terrestrial globe in titanium, relief-engraved continents, ocean blue treatment
Day-and-night UTC indicator in titanium, engraved and lacquered
GMT indicator in gold
Amphitheatre hour-ring with engraved and lacquered minute-circle
Small seconds indicator in gold
MOVEMENT SIDE
Synthetic sapphire disc displaying city names surrounded by 2 rings (UTC and summer time) engraved and lacquered, hand matt lapped
Gold “summer time” plate with limitation number, raised engraving, hand matt lapped
HANDS
Hours and minutes, red triangles with Super-LumiNova
2nd time zone GMT indicator, red triangle
Small seconds in polished blued steel, flat black polished head
STRAP AND CLASP
Hand-sewn textured rubber or rubber with text in relief
Titanium folding clasp, engraved GF logo
On demand: 3-row metal bracelet in titanium, folding clasp with integrated fine adjustment, engraved GF logo
