reubel Forsey delivers a new generation of carbon timepieces. The material becomes part of the Atelier’s collections, offering collectors enhanced lightness and resistance.

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.

It was no mean feat to produce the convexe carbon case. 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.

For Greubel Forsey, this specific technique opens up the possibility of executing fine watchmaking finishing by hand that affirm the Atelier’s identity and status. This is how you’ll come to find finishes, from satin to matte and relief engraving on the Double Balancier Convexe, all complementing the natural work of the carbon fibres that Greubel Forsey has taken care to match with the converging lines on the convexe case. This is carbon deployed at its best, both flexible and solid, with fibres between 1 and 5 microns thick, perfectly defined and mastered.

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 mainplate 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.

A truly unique expression of this sixth Fundamental Invention, while the invention itself has never stopped evolving. 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. In this unprecedented compact version with a diameter of 42.5mm, only 22 pieces will be produced in each variation of the Double Balancier Convexe carbon.

TECHNICAL SPECIFICATIONS

Movement
Hand-wound movement with 2 patents
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
• Openworked 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

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

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”
Case dimensions
• 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
• Water-resistant 5 atm - 50 m - 164 ft (standard NIHS 92-20/SN ISO 22810:2010)
Crown
• Carbon, hand-finished with GF logo

Strap and clasp
• Non-animal material, rubber with texture in relief, titanium and carbon folding clasp, engraved GF