Huygens’ invention of the hairspring in 1675 was a milestone in watchmakers’ long pursuit of precision. However, it doesn’t eliminate the problem of gravity, which is detrimental to the timekeeping of the copy watch, especially in a vertical position. To solve this problem, Abraham-Louis Breguet (1747-1823) conceived the idea of mounting the regulating mechanism (spring, balance and escapement) in a rotating frame. By turning around an axis, usually within a minute, the frame brings the “heart” of the watch into different successive positions, thus averaging the timing changes. Birth of the tourbillon (1801).
To further improve timekeeping, Robert Greubel and Stephen Forsey reimagined the tourbillon principle and then developed their first three fundamental inventions: Double Tourbillon 30° (2004), Quadruple Tourbillon (2005) and 24-Second Tourbillon (2006).
In their GMT Quadruple Tourbillon, the two watchmakers chose to revisit their second invention and take it a step further by combining it with a multi-time zone display.
Robert Greubel and Stephen Forsey showed inventiveness when they combined their second fundamental invention, the quadruple tourbillon, with their pioneering interpretation of the GMT and its oversized rotating globe. Bold and bold. Displaying three time zones and a universal time function, this remarkable timepiece has a unique three-dimensional architecture crafted with exquisite craftsmanship.
According to the principle that the more different the position of the adjustment mechanism moves, the more precise the timekeeping is, Robert Greubel and Stephen Forsey invented the quadruple tourbillon with spherical differential.
From the initial idea, the concept was clear. While it would be challenging to couple four separate tourbillons, they sought a more compact solution. To save space in all three dimensions, they chose to build the tourbillons in pairs in a unique compact cage system, an extremely challenging feat. Each of these two systems is modeled on a 30° double tourbillon, with the first cage rotating at 30° in one minute, mounted in the second upright cage, and completing a full in four minutes rotate.
The inclination of the inner cage, combined with the different rotational speeds of the two cages, focuses on eliminating timekeeping changes due to the Earth’s gravity when the replica men watch is in all usual positions, especially in the stable position. A spherical differential is used to average the timing of the two autonomous oscillators to improve timing performance, and the system has been awarded two patents.
Having mastered the tourbillon, Robert Greubel and Stephen Forsey continued to research and reinterpret other watch mechanisms, in particular one practical and much appreciated complication: the simultaneous display of multiple time zones. In 2011, two Inventor watchmakers expressed their vision for this modern feature in this groundbreaking timepiece, aptly named GMT, and recently joined by GMT Earth. In this patented system, the second time zone display on the separate sub-dial combines with the universal time display to provide an intuitive world time readout thanks to a world first: an oversized earth completes a full revolution every 24 hours, Follow the planet Earth itself.
In combining the quadruple tourbillon with the GMT mechanism, Greubel Forsey copy not only accomplished a major technical feat, but also created a new hand-wound movement composed of 705 parts, including Three rapidly spinning barrels. Inventor watchmakers also tackled this challenge from an architectural point of view, creating a timepiece that expresses a 3D approach on multiple levels. The main hour/minute dial between 1 and 2 o’clock forms the highest point of the dial, highlighted by the case’s subtle asymmetry, complemented by a 72-hour chronograph power reserve display. The next level is at 4 o’clock, where the coaxial small seconds and the second time zone display are adjustable in one-hour increments via push-buttons. between 8:00 and 9:00,
Lateral windows in the asymmetrical part of the case provide unprecedented views of the equator and the southern hemisphere. The four tourbillons are drawn in two pairs on either side of the blue planet, each with an open and transparent structure, held in place by flat black polished bridges, decorated with gold sleeves and hand-polished bevels and countersinks.
The world time is visible through the case back, with a fixed 24-hour scale marking the day/night zone and a disc with three-letter abbreviations representing 24 cities in different time zones. The disc also distinguishes in light colors the time zones that implement daylight saving time (Daylight Saving Time); and those that don’t (displayed on a dark background). The caseback also offers an opportunity to admire the quadruple tourbillon as well as the frosted bridge with jewels set in a gold sleeve. The two complex asymmetrical convex sapphire crystals that protect the dial and caseback also require a high level of expertise.
This contemporary aesthetic masterpiece is available in a unique version of 66 pieces. The first edition of the 11 models is in white gold and is numbered 01/11 to 11/11 on a plate in the center of the dial.
Model: GMT Quadruple Tourbillon
Unique Edition 66 pieces
11 white gold
Manual winding movement with 3 patents
GMT • Second time zone • Global time and day and night rotating globe • Universal time in 24 time zones • Summer time for city view • Horizontal window showing equator and southern hemisphere • GMT pusher • Quadruple tourbillon • Hours and minutes • Small seconds • Power reserve
number of parts
• Movement: 705 parts
• Four tourbillon cages: 260 parts
• Total frame weight: 2.25 grams
• Spherical aberration: 28 parts
Number of jewels: 84; olive dome jewels in a gold sleeve
Chrono power reserve: 72 hours
Barrels: Three fast-rotating barrels connected in series (one revolution in 3.2 hours), one of which is equipped with a sliding spring to avoid excessive tension
Balance wheel: variable inertia with platinum averaging time screw (diameter 10.70 mm)
Frequency: 21,600 vibrations/hour Balance wheel
Hairspring: Phillips end curve; Geneva style stud
Motherboard: Nickel silver, matte and speckled, polished bevel and countersunk, ruled sides, nickel palladium finish
Bridges: Nickel-silver, matte and speckled, polished chamfered and countersunk, straight-grained sides, nickel-palladium finish; gold plate with individual number engraved; flat black polished gold plate with embossed text, polished bevel and countersunk, straight Grained sides; four flat black polished steel tourbillon bridges, hand-polished chamfers and countersinks, straight grained sides
• Tilt 30°, 1 rotation per minute
• 1 spin in 4 minutes
• Hand-chamfered and hollowed-out cage posts
• Each double cage comes with 1 gold weight, individually numbered
• Involute circular profile
• Conical gears with profiled teeth
hours and minutes
Small seconds (average performance)
72 hours power reserve,
Second time zone Greenwich Mean Time
24 time zones Universal Time
Rotating Titanium Ball with Universal Time
City Watch Summer Time
day and night
White gold case, asymmetric cabochon synthetic sapphire crystal
Transparent case back, asymmetric convex synthetic sapphire crystal
Side window, profiled synthetic sapphire crystal
3D variable geometry lugs
Raised polished engraving “GMT Quadruple” and “Greubel Forsey” on hand-punched background
golden security screw
Polished bezel with hand-brushed case
White gold GMT button with raised engraving on hand-punched background
Hand engraved personal number
Water resistance: 3 atm – 30 m – 100 feet (Standard NIHS 92-20/SN ISO 22810:2010)
Crown: white gold, black lacquered GF logo
Multi-layered gold, anthracite
Gold hour ring, round grain, polished bevel, black finish
golden hour markers gold
Power reserve and GMT, hand-finished
Small seconds, round grain
Polished Gold Hour and Minutes with Super-LumiNova
Small seconds in polished stainless steel, polished stainless steel with black finish
Power reserve, hand polished counterbore
Second time zone GMT indicator, red
Hand-stitched alligator leather
White gold folding clasp, hand-engraved GF logo