Greubel Forsey │ New Creations │ SIHH 2018

Robert Greubel and Stephen Forsey took up a significant challenge with the GMT Earth: how to offer a comprehensive, three-dimensional view of the terrestrial globe, from the North to the South Poles. They approached the architecture of this timepiece from a different angle to give the movement and the case a more prominent role.

360° view
With this new creation, Robert Greubel and Stephen Forsey are once again pushing the envelope and venturing into uncharted territories. The GMT Earth provides an amazing 360° view of our planet Earth all the way from the North to the South Pole. This technical feat was achieved by an original movement architecture in relation to the case shape and dimensions. Revealing the entire terrestrial globe required complex application of sapphire crystal, a skill which Greubel Forsey has acquired over many years of research and utilization.

3D view
The globe is not the only three-dimensional element in this timepiece – it’s a characteristic that features at every level. The three-dimensionality first appears at the highest point of the dial, with the hour, minute and small seconds indications. Then the gaze glides gently across the GMT indication with its triangular red hand, followed by the power reserve indication displayed by a long, slender hand. Finally, our eyes come to rest on the lowest part of the dial, which shows the globe alongside the Tourbillon 24 Secondes, Greubel Forsey’s 3rd pivotal Invention.

Global view
The GMT Earth enables a clear view of three time zones simultaneously to within a quarter of an hour. Furthermore, on the movement side of the timepiece, 24 time zones are displayed with the summer and winter times to complement the universal time indicated by the terrestrial globe.

The proportions of the case were constructed to accommodate the high-domed sapphire crystal bezel and the special artistry on the caseband. The characteristic lateral plates bearing engraved inscriptions that encapsulate the key values of Robert Greubel and Stephen Forsey decorate the case body.

This white gold edition is limited to 33 pieces.

GMT Earth
Limited edition of 33 pieces in white gold
Hand-wound movement with 3 patents

GMT • 2nd time zone • rotating globe with universal time and day-and-night • complete and global view from northern to southern hemisphere • universal time on 24 time zones • summer and winter time • cities observing summer time • lateral window showing the equator • GMT pusher • Tourbillon 24 Secondes • hours and minutes • small seconds • power-reserve

Movement

Movement dimensions
• Diameter : 36.40 mm
• Thickness : 11.55 mm

Number of parts
• Movement : 453 parts
• Tourbillon cage : 86 parts
• Weight of the cage : 0.39 g

Number of jewels
• 60
• 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

Balance wheel
• Variable-inertia with gold mean-time screws (10 mm diameter)

Frequency
• 21’600 vibrations/hour

Balance spring
• Phillips terminal curve
• Geneva-style stud

Main plates
• Nickel silver, frosted and spotted with polished bevelling and countersinks, straight-grained flanks, nickel-palladium treatment

Bridges
• Nickel silver, frosted with polished bevelling and countersinks, straight-grained flanks, nickel-palladium treatment
• Flat black polished steel tourbillon bridge, hand-polished bevelling and countersinks
• Flat black polished steel screws, blued by heat treatment

Tourbillon
• Inclined at a 25° angle, 24-seconds rotation
• Light alloy cage pillars
• Titanium cage bridges
• Gold counterweight

Gearing
• Involute circle profile
• Tangential inclined gear on fixed wheel and profiled teeth on escape wheel pinion

Displays
• Hours and minutes
• Small seconds
• 72-hours power reserve on a sector
• 2nd time zone GMT
• 24 time zone universal time
• Rotating titanium globe with universal time
• Complete view from North Pole to South Pole
• Summer time
• Day-and-night

Exterior

Case
• In white gold, with 18k gold plates, engraved, hand-finished with text, screwed to the caseband
• Lateral window with shaped synthetic sapphire crystal
• Three-dimensional, variable geometry-shaped lugs
• Three-dimensional synthetic sapphire crystal caseback, with integrated dome
• Three-dimensional, asymmetrical, synthetic sapphire crystal bezel
• Raised polished engraving “GMT Earth” and “Greubel Forsey” on a hand-punched background
• Gold security screws
• White gold GMT pusher with raised engraving on a hand-punched background
• Hand-engraved individual number

Case dimensions
• Diameter : 45.50 mm
• Height : case 16.18 mm (height on synthetic sapphire dome 18.00 mm)

Water resistance of the case
• Water-resistant 3 atm – 30 m – 100 ft (standard NIHS 92-20/SN ISO 22810:2010)

Crown
• In white gold, synthetic sapphire insert with GF logo

Dial side
• Multi-level hour-ring in synthetic sapphire, galvanic growth hour indexes, engraved and lacquered minutes and small seconds
• Power-reserve and GMT indicators in gold, engraved and lacquered, hand matt lapped
• Rotating globe with day-and-night UTC indicator in synthetic sapphire, engraved and lacquered

Movement side
• Synthetic sapphire disc displaying city names surrounded by 2 gold rings (UTC and summer time)
engraved and lacquered
• Gold “summer time” plate with individual number, raised engraving
• South Pole of the globe with UTC indicator, engraved and lacquered, hand matt lapped

Hands
• Hours, minutes, small seconds and power-reserve in polished steel, black treatment, hand-polished countersinks
• 2nd time zone GMT indicator, red triangle

Strap and clasp
• Black rubber or hand-sewn alligator
• White gold folding clasp, hand-engraved with the GF logo

Greubel Forsey presents the Double Balancier in 5N red gold featuring a black gold and enamel dial at the Salon International de la Haute Horlogerie 2018 (SIHH).

Mechanical marvel
With this latest version, Robert Greubel and Stephen Forsey sought to play up the Double Balancier’s theatrical side. The black gold dial with the minutecircle, numerals, hour markers and power reserve in champlevé grand feu (oven-fired) enamel functions like a curtain rising to reveal the phenomenal duet of the two balance wheels connected by the constant differential. A rotation indicator fitted to the differential executes one complete turn in 4 minutes. The heart of the mechanism and its the threedimensional architecture reveals a true horological spectacle and each of the hand-decorated elements plays its own role in this mechanical opera.

First-rate chronometric performance
The revolutionary mechanism in the Double Balancier pushes the limits of timekeeping. Two inclined balances optimise performance in stable positions, while the Constant Spherical Differential provides more steady amplitude.

In 2009, after extensive research on multiple regulators at Greubel Forsey’s EWT (Experimental Watch Technology) Laboratory, the inclined Double Balancier was introduced as a prototype at Baselworld. It was Greubel Forsey’s 6th Fundamental Invention. The two inclined regulating organs – then positioned on top of each other – now occupy distinct and separate three-dimensional spaces. This new configuration further develops chronometric performance while the Constant Spherical Differential cuts the timing variations in half.

Three-dimensional architecture
Aesthetically, this timepiece is both understated and complex. A wide aperture catches the eye with powerful three-dimensional aspects, extensively revealing the heart of the mechanism. We are diving into an architectural world built on many levels, a miniature futuristic city constructed between the balances whose inclination is decidedly dizzying. The 5N red gold hands and matching case amplify the noble aura of this timepiece.

Double Balancier
In 5N red gold
Hand-wound movement with 2 patents

Double Balancier • hours and minutes • small seconds • 4-minutes spherical constant differential rotation • power-reserve

Movement

Movement dimensions
• 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

Bridges
• 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, straight-grained flanks
• 2 engraved gold plates (1x Greubel Forsey, 1x individual number)

Escapement platforms
• 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

Gearing
• Involute circle profile
• Inclined gear with profiled teeth on fourth wheel

Displays
• Hours and minutes
• Small seconds
• 4-minutes spherical constant differential rotation
• 72-hours power reserve on a sector

Exterior

Case
• In 5N red gold with convex synthetic sapphire crystal
• 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

Case dimensions
• Diameter : 43.00 mm
• Height : 13.38 mm

Water resistance of the case
• Water-resistant 3 atm – 30 m – 100 ft (standard NIHS 92-20/SN ISO 22810:2010)

Crown
• In 5N red gold with engraved and black lacquered GF logo

Dial
• Multi-level black anthracite gold dial, with engraved and “oven fired” enamelled indexes (émail grand feu champlevé)
• Differential rotation and small seconds indicators in gold

Hands
• Hours and minutes in polished gold, with Super-LumiNova
• Small seconds, 4-minutes in polished blued steel
• Power-reserve in polished gold

Strap and clasp
• Hand-sewn alligator
• 5N red gold folding clasp, hand-engraved with the GF logo

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