Greubel Forsey During Geneva Watch Days 2021, Greubel Forsey launched the third and final interpretation of its GMT Earth. Made of titanium, this intense black version is a limited edition of 11 pieces.
The GMT Earth by Greubel Forsey is an extraordinary wristwatch that, for the first time, makes it possible to appreciate the entirety of the world in a single glance.
This technical feat first appeared in 2011. At the time of the first “GMT”, the Earth was not yet fully revealed. Seven years later, the design of the Earth was finally complete: visible from all angles in its new sapphire alcove, it appears as though it is floating in space. On the front as well as the back, the laser-engraved Earth shows world times that are both quick and easy to read.
The first version of the GMT Earth was in white gold. The second was in platinum. Now, this timepiece is available with a new titanium case. The GMT Earth in titanium will be available in a limited edition of 11 pieces, three times less than the original version. Weighing just 117g, the weight of the strap has been reduced by two-thirds. The case has lost just over a third of its weight.
Titanium is used not only for the entire case, but also the bridges, the GMT push-piece, the crown and the folding buckle, the latter two being the components most exposed to shocks and scratches.
To accompany the light and matt tones of titanium, Greubel Forsey opted for a black finish on the dial. It is applied to the spotted bottom plate and to all the frosted bridges, with straight flanks, polished bevelling and countersinks. This finish is also featured on an all-black natural rubber strap, whose inner face is engraved with the cardinal values of the Greubel Forsey Atelier and which are visible on the bezel.
The GMT Earth displays four key pieces of information on its dial side. The first is the off-centre hours, minutes and seconds display. The first two feature large open-worked hands finished with a Super-LumiNova tip, complemented by a small seconds hand on a sapphire disc at three o’clock.
On the left is the GMT indicator, whose red hand effortlessly stands out against a hand-engraved black gold disc filled with lacquer. The third, located opposite the crown, is the power reserve, designed following the same process: a black, engraved gold segment, filled with lacquer and covered by a silver-polished steel hand.
Finally between 7 o’clock and 9 o’clock, the Earth occupies the largest space, completing a full rotation in 24 hours. The engraved sapphire ring around the equator acts as a day / night indication and allows you to instantly see which hemisphere is in the daytime and which is at night.
Located on the side of the caseband, a final window opens to show the equator. Thanks to this, the Earth really can be seen from all angles.
Finally, on the caseback side, the worldtime display indicator completes the design. 24 time zones indicate the UTC of 24 major cities – with those that observe daylight savings on a white background.
The GMT Earth boasts Greubel Forsey’s third invention Tourbillon 24 Secondes, which uses a fast rotation speed and is set at an angle to resolve the positioning problem in relation to gravity and which is crucial for the operation of the oscillator. The 25° angle and the rapid rotation of the tourbillon cage significantly improve the chronometric performance of a system containing only one tourbillon, especially those in fixed positions.
Technical details
Model: Greubel Forsey GMT Earth Titanium Final Edition
Edition
Limited edition of 11 pieces in titanium
Special features
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 indicator
Movement
Hand-wound movement with 3 patents
Movement dimensions
• Diameter: 36.40mm
• Thickness: 11.55mm
Number of parts
• Movement: 453 parts
• Tourbillon cage: 86 parts
• Weight of the cage: 0.39g
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 (10mm diameter)
Frequency
• 21’600 vibrations/hour
Balance spring
• Phillips terminal curve
• Geneva-style stud
Main plate
• Nickel silver, frosted and spotted with polished bevelling and countersinks, straight-grained flanks, black treatment
Bridges
• Nickel silver, frosted with polished bevelling and countersinks, straight-grained flanks, black 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 zones universal time
Rotating titanium globe with universal time
Complete view from North Pole to South Pole
Summer time
Day-and-night
Exterior
Case
In titanium, with titanium 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
Titanium GMT pusher with raised engraving on a hand-punched background
Engraved individual number
Water-resistance: 3atm – 30m – 100ft (standard NIHS 92-20/SN ISO 22810:2010)
Case dimensions
Diameter: 45.50mm
Height: case 16.18mm
Height on synthetic sapphire dome: 18.00mm
Crown
In titanium, 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, circular-grained, black treatment
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, hand-polished countersinks
2nd time zone GMT indicator, red triangle
Strap and clasp
Rubber or hand-sewn alligator
Titanium folding clasp, engraved with the GF logo