Greubel Forsey has released a carbon version of the Double Balancier Convexe 42.5mm watch. This is the very first carbon timepiece from Greubel Forsey. It shares the Atelier’s boldness combining structural complexity with the style of a highly technical material.
Recognised and appreciated by collectors, the convexe case fully benefits from this design choice. On the case back, its form perfectly meets the curve of the wrist. On the dial, a three-dimensional, curved profile allows the movement to fully express itself. Since carbon fibres are never combined twice in the same way, the design of each piece will also be unique, reinforcing the exclusivity of the timepiece.
The carbon case, as developed by Greubel Forsey, requires pressure 8 times greater than average (16 tonnes applied to a convexe case, compared to an industry standard 2 tonnes). This mechanical effort makes it possible to obtain a much denser carbon for an almost identical weight, to be enjoyed by the collector.
The timepiece has a considerably more modern feel, perfectly in line with the direction of the signature brand. This is also the reasoning behind the reduced diameter of 42.5mm on the Double Balancier Convexe.
Greubel Forsey demonstrates the power of these new carbon timepieces from the outset by offering its collectors two versions with strong assertive character.
The first features a dominant iridescent green finish, with numerous rich blue hues to the main bridge incorporating the power reserve display, as well as the main-plate and the hour ring. This is complemented by a rubber strap in the same tone, creating a fresh feel and reinforcing the signature brand’s contemporary commitment.
The second version brings black to the fore, asserting the timepiece’s elegant simplicity. The carbon fibre weaves a homogeneous, decidedly contemporary configuration.
By contrast, the salient feature that stands out most is the hand-finished movement, with its mirror polishing, sharp internal angles, straight and circular-grained surfaces, and curved hands with luminescent tips. In both the green and black versions, the Double Balancier’s calibre exudes technicality and precision.
Double Balancier is the sixth Fundamental Invention by Greubel Forsey. Its prototype mechanism was patented in 2007. It was first proposed as part of an EWT (Experimental Watch Technology) project, in which the two regulating organs were superimposed and inclined at 20°. A second calibre of just six timepieces followed close behind, with the two regulating organs positioned on three-dimensional planes and inclined, this time at 35°.
In 2016, Greubel Forsey presented the invention in its current form: the two balance wheels are arranged side by side, inclined at 30°, and linked by a constant spherical differential visible between 6 and 7 o’clock. In each 4-minute period, it halves the margin of error and meets the performance, precision and reliability requirements that Greubel Forsey sets for all its timepieces.
Only 22 pieces will be produced in each variation of the Double Balancier Convexe carbon.
Technical details
Model: Greubel Forsey Double Balancier Convexe Carbon 42.5mm
Movement and functions
Special features
Hand-wound movement with 2 patents
Double Balancier
4-minutes spherical constant differential rotation
Movement dimensions
Overall diameter: 37.70 mm
Thickness: 9.46 mm
Number of parts
Movement: 371 parts
Escapement platform: 2 x 70 parts
Spherical constant differential: 30 parts
Number of jewels: 50, Olived-domed jewels in gold chatons
Chronometric power reserve
72 hours
Barrels
Two coaxial series-coupled fast-rotating barrels (1 turn in 3.2 hours), one of which is equipped with a slipping spring to avoid excess tension
Relief-engraved text, circular-grained, green or black treatment, polished chamfer
Balance wheel
Variable-inertia with gold mean-time screws (10mm diameter)
Frequency: 21’600 vibrations/hour
Balance springs
Phillips terminal curve
Geneva-style stud
Anti-shock system with gold pin
Bridges and main plates
Titanium
Frosted, polished bevelling and countersinks, green or black treatment according to the version
Multi-level, openworked centre bridge, polished bevelling and countersinks
Movement side
Flat black polished steel differential bridge
Gold plate with engraved limitation number, circular-grained, polished bevelling and countersinks, straight-grained flanks
Escapement platforms
Inclined at a 30° angle
Steel, straight graining, hand-polished bevelling and countersinks
Polished steel pillars
Open-worked steel balance wheel bridges, hand-polished bevelling and countersinks, flat black polished
Gearing
Involute circle profile
Inclined gear with profiled teeth on fourth wheel
Displays
Hours and minutes
Small seconds
4-minutes spherical constant differential rotation
Power reserve on a sector
Exterior
Case
Carbon and titanium with curved synthetic sapphire crystal
Three-dimensional, variable geometry-shaped bezel, hand-finished
Profiled lugs, screwed fixing
Transparent back with curved synthetic sapphire crystal
Titanium security screws
Raised engraving “Double Balancier” and “Greubel Forsey”
Caseband diameter: 42.50 mm
Bezel diameter: 44.40 mm
Case height: 13.75mm
Height on synthetic sapphire crystals: 14.35 mm
Water resistance of the case: 5 atm – 50 m – 164 ft (standard NIHS 92-20/SN ISO 22810:2010)
Crown: Carbon, hand-finished with GF logo
Dial side
Three-dimensional, variable geometry hour-ring with engraved and lacquered minute-circle
Three-dimensional, variable geometry hour indexes, polished, with Super-Luminova
Power-reserve indicator, engraved and lacquered
Differential rotation and small seconds indicators in gold
Hands
Hours and minutes, curved profile, polished steel with Super-Luminova
Power-reserve, 4-minutes and small seconds in polished steel, blued according to the version, flat black polished head
Strap and clasp
Non-animal material, rubber with texture in relief, titanium and carbon folding clasp, engraved GF
