Greubel Forsey Unveils Two New Balancier Convexe S² Models at Geneva Watch Days 2023
Double Balancier Convexe
Pressing carbon to its limits
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.
Style at the service of performance
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 matt 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.
One case, two versions
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.
The majestic Double Balancier
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, with the first available from August 2023.
Balancier Convexe S²
Carbon is a material that Greubel Forsey has studied for many years. Giving it complex, architectural shapes, all with the highest level of watchmaking finishes, is an exercise that requires patience and technical mastery. Now, the conditions are ripe to give life to the new Balancier Convexe S2, one of the Atelier's iconic creations.
The new diameter of 41.5 mm has been specifically designed for carbon. It’s a radical change, immediately visible on the wrist. This timepiece is tighter, livelier, and even more modern. The very dark tone of the carbon reinforces the feeling of a very compact piece, while staying open to display the movement, complication and finishes.
16 tonnes Per Square Centimetre
From a technical perspective, the challenge was significant. To impose as complex a geometry on carbon as that of the Balancier Convexe S2 convexe case is an unprecedented move in watchmaking. It requires a precise combination of temperature and pressure. Heat makes the carbon more flexible to work with; pressure gives it its shape. A conventional case usually requires 2 tonnes of pressure per square centimetre. For Greubel Forsey's signature convexe case, it was necessary to apply 16 tonnes: 8 times more than is conventional.
By multiplying the layers of carbon, each of which measures 1 to 5 microns, Greubel Forsey has obtained a much denser carbon case, revealing the perfect combination of technique and aesthetics so well known to the Atelier manufacture.
Each case is individually enhanced by the arrangement of its fibres, carefully controlled by Greubel Forsey to create the perfect profile. The direction of the carbon fibres is a top priority, so that they align with the curvature of the convexe case, which is underlined by the hand finishing.
Convexe on the case back as well as the display side, the timepiece hugs the wrist perfectly. At 12 and 6 o'clock, the two converging lines give the Balancier Convexe S2 a 3D geometry of unequalled complexity. It delivers an unprecedented volume, giving way to a vast open space under the sapphire crystal at 6 o'clock. Within, the 30° Inclined Balance Wheel that has been completely redesigned to fit the new proportions of the carbon case, has plenty of space.
A feat of finishing
As always with Greubel Forsey, finishing is a crucial stage in developing a timepiece. For its carbon version, the new Balancier Convexe S2 has stuck to traditional finishes for the case, lugs and crown. The bezel and lugs alternate between matt and grained finishes. The crown asserts a bold matt finish. The engraving is of note: always in relief for the convexe case, and remaining so on this carbon case – with particular attention accorded to the precision of the "GF" initials, finishing flush with the centre of the crown.
Between 3 and 4 o'clock is the double openworked "arched" bridge. Its train of wheels below seems somehow suspended as if in a void. With its patent filed in 2019, the bridge has also become one of Greubel Forsey's aesthetic signatures. It embodies a very powerful, creative vision of fine watchmaking, along with an extremely high level of finish on the titanium components (which are notoriously difficult to polish), with multiple sharp internal angles.
The 303-part movement delivering a 72-hour chronometric power reserve has a perfectly defined architecture, with three large hand-decorated bridges on the movement side. The grained bridges and main plate are perfectly harmonised with the carbon case. The cover of the twin barrels now features a black treatment in keeping with the case and carbon plate. Finally, the relief engraving on the 3D barrel cover blends seamlessly into the redesigned case.
The new Balancier Convexe S2 will be produced in two limited editions of 22 pieces each, the small seconds with blue or black treatment, matching textured rubber strap, and a titanium and carbon buckle.