Presented at the Salon International de la Haute Horlogerie 2016 (SIHH), the first Double Balancier à Différentiel Constant by Greubel Forsey pushes the limits of timekeeping. Two inclined balance wheels optimise performance in stable positions, while the Differentiel Spherique Constant provides more steady amplitude.
Aesthetically, this timepiece is both understated and yet complex. The eye-catching wide aperture with powerful three-dimensional aspects, extensively reveals the heart of the mechanism.
Robert Greubel and Stephen Forsey began to research multiple regulators in 1999 as part of their EWT (Experimental Watch Technology) platform.
The first prototype to feature a fixed oscillator, the Double Balancier Incliné, was presented at Baselworld in 2009, as the sixth Greubel Forsey invention.
The two inclined balance wheels – initially positioned one above the other – now occupy distinct and separate three-dimensional spaces. This new configuration is responsible for improved chronometric performance, while the Differentiel Spherique Constant cuts the margin of error in half.
Once again, this timepiece stands out by virtue of the extreme attention paid to its finishing. These include the three-dimensional, geometric lugs and the raised, polished engraving on a hand-punched background.
The Greubel Forsey Double Balancier Unique Edition is comprised of 33 pieces in white gold, which will be followed by other, non-limited versions.
Model: Greubel Forsey Double Balancier Unique edition, white gold version
Limited to 33 pieces in white gold
Hand-wound patented movement • Patents pending Double balancier • hours and minutes • small seconds • 4-minutes spherical constant differential rotation • power-reserve
Diameter: 36.40 mm
Thickness: 8.15 mm
Number of parts
• Movement: 285 parts
• Escapement platform: 2 x 71 parts
• Spherical constant differential: 30 parts
Number of jewels: 50; 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 wheels: Variable-inertia with gold mean-time screws (10 mm diameter)
Frequency: 21’600 vibrations/hour
Balance springs: Phillips terminal curve; Geneva-style stud
Main plates: Nickel silver, frosted and spotted, with polished bevelling and countersinks, straight-grained flanks, grey PVD treatment
• Nickel silver, spotted, with polished bevelling and countersinks, straight-grained flanks, grey PVD treatment
• Flat black polished steel differential bridges
• Flat black polished gold centre bridge, with polished bevelling and countersinks, straightgrained flanks
• 2 engraved gold plates (1x Greubel Forsey, 1x individual number)
• Inclined at a 30° angle
• Nickel silver, straight graining, hand-polished bevelling and countersinks, nickel-palladium treatment
• Polished steel pillars
• Flat black polished and barrel polished steel balance wheel bridges
• Involute circle profile
• Inclined gear with profiled teeth on fourth wheel
Hours and minutes
4-minutes spherical constant differential rotation
72-hours power reserve on a sector
In white gold with convex synthetic sapphire crystal
Diameter: 43.00 mm
Thickness: 13.38 mm
Transparent back with synthetic sapphire crystal
Three-dimensional, variable geometry-shaped lugs
Raised polished engraving “Double Balancier” and “Greubel Forsey” on a hand-punched background
Gold security screws
Hand-polished bezel, caseband with hand-finished straight graining
Hand-engraved individual number
Water-resistant: 3 atm – 30 m – 100 ft (standard NIHS 92-20/SN ISO 22810:2010)
Crown: In white gold with engraved and black lacquered GF logo
Multi-level gold dial, silvered with engraved and “oven fired” enamelled indexes (émail grand feu champlevé)
Differential rotation and small seconds indicators in gold
Hours and minutes in polished gold, with Super-LumiNova
Small seconds, 4-minutes and power-reserve in polished blued steel
Strap and clasp
White gold folding clasp, hand-engraved with the GF logo