Greubel Forsey GMT Earth Limited Edition, White Gold Case

The GMT Earth timepiece from Greubel Forsey offers 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.

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.

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.

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.

Technical details

Model: GMT Earth
Limited edition of 33 pieces in white gold

Movement

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 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 beveling 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
Diameter: 45.50 mm
Height: case 16.18 mm (height on synthetic sapphire dome 18.00 mm)
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
Water resistance of the case: 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

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