Hands-on Greubel Forsey GMT Quadruple Tourbillon

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Greubel Forsey is, year by year, a pioneer in watchmaking. There is not a year when the independent brand did not amaze us with exceptional pieces. One of the last year’s masterpiece is the Greubel Forsey GMT Quadruple Tourbillon.

Review Greubel Forsey GMT Quadruple Tourbillon

When I visited Baselworld 2019, I had no idea, like all of us what the future will bring. The actual situation left us without the most important watch events of the year. Many pieces were not even launched and the ones that have seen the light were viewed by a handful of people. So I am considering myself lucky that I got the chance, even if it was last year to have in my hands the Greubel Forsey GMT Quadruple Tourbillon. This piece is utterly gorgeous. In appearance and in the engineering involved…

GMT timepieces have a history under the patronage of Greubel Forsey. The last one being Greubel Forsey GMT Sport, launched last winter. The piece reviewed today was launched during Baselworld 2019. The pieces evolved continuously as the brand research and development reached new breakthrough.

Asymmetrical case

Those familiar with Greubel Forsey pieces will find already familiar the case of the GMT Quadruple Tourbillon. The 46.5 mm case is manufactured in gold (Unique edition of 66 pieces, 11 pieces in white gold).

The slightly curved caseband suffered a vertical brushing, while the rest of the case’s elements are mirror polished. Between 8 and 9 o’clock we find the first protuberance. Behind a curved crystal is visible the GMT sapphire disk and the Earth.

The right side of the case features the crown in the traditional position, the GMT pusher at approx. 4 o’clock and the second protuberance fitting the actual time-telling dial.

The crown is engraved with the brand logo. The pusher is positively engraved with “GMT” on a hand-punched background. A time-consuming engraving technique requires skill and precision.

The watch is fitted a hand-sewn alligator strap and white gold folding clasp decorated with a hand-engraved with the GF logo medalion.

A multi-act spectacle dial

Greubel Forsey GMT Quadruple Tourbillon is, by a mile, a spectacular appearance. Even a complete horological agnostic person will be attracted by this complex machinery. The original display is not easy to hide under the sleeve.

The watch displays hours and minutes on the upper right dial. The hours and minutes hands are manufactured in polished gold, with Super-LumiNova insert. The subdial includes the 72-hours power reserve on a sector with a screwed separate indicator plate. The power-reserve’s hand is realised in polished steel and decorated with a hand-polished countersink.

The 4 o’clock subdial displays the running seconds in polished steel with black treatment named mean performance. The red hand shows the 2nd time zone GMT.

The spectacular Earth display at the lower left side of the watch shows the 24 time zones universal time, including day and night indication.

On the backside, there is a second dial displaying the universal time with a fixed 24 hours scale (again with day/night indication) and a disk bearing 24 cities observing summer time (Daylight Saving Time) appearing in a light colour.

An exceptional calibre

The Greubel Forsey GMT Quadruple Tourbillon is powered by a new hand-wound calibre. This 805 parts calibre comprises 4 tourbillons connected via a spherical differential. See the official drawing below.

To achieve the watch we see today, many complex steps were needed. The brand’s Quadruple Tourbillon runs back to 2008 with four tourbillon side by side. In 2011 came the Invention Piece 2 with tourbillons separated from position. The mirror structure with double cages presents to the viewer the hairspring on the top pair and the fixed wheel view on the lower pair. So from each side of the piece, you have the head and tail view of the cages. The complexity of the mirror image construction meant also having the rotation reversed (mirrored).

The design is complicated, the execution extremely elaborated. Considering that each of these elements adds its own error, the power-hungry house, the 72 hours chronometric power reserve achieved from the three series-coupled fast-rotating barrels is amazing.

The four tourbillons, organised in two pairs are placed on a 30° angle on the sides of the GMT blue planet. The mirrored cages have different rotations speeds. The first cage is rotating in one minute. The second upright cage performs a full rotation in four minutes.

The tourbillons are fixed using gold chatons with hand-polished bevelling and counterinks and flat black polished bridges.

And the backside view of the tourbillon 1+2:

The lower tourbillons, the pair 3+4 offers the same spectacle but mirrored.

And the backside of the lower pair:

or this, more natural view:

The finishes are Greubel Forsey. That means best of the best of the best (…Sir! – paraphrasing Will Smith in MIB). Just have a look at the pictures and enjoy. Better of course with the piece itself in the hands.

Final words

So you take the already technically exceptional Quadruple Tourbillon and the gorgeous GMT and put them together. The result is a spectacle reserved for a few. The breathtaking show is split partly to theatrical construction, partly to the finishes. The brand “throw” of finishes makes watchmaking looks easy. We all know (or we must) that is not that easy. The amount of work involved is partly unpaid.

On my small wrist, the Greubel Forsey GMT Quadruple Tourbillon is a large but exceptional good looking presence. I usually stop at 41 mm when considering comfortable pieces. But somehow, the “greatness” (metaphoric sense) of this piece overwhelms the greatness of seise and weight. Anyway, if you are used to a platinum or gold bracelet watch, this will not feel different. Somehow, it feels very right on the wrist.

We need to give Cesar its silver… The watch is a spectacular technical achievement. The brand is actively fighting into keeping the traditional horological values and techniques. Just have a look and the Naissance d’une montre series, the involvement with Time Æon Foundation (Interview: David Bernard of Time Æon Foundation). And we need to thank the people investing money and time in this kind of pieces. Partly due to the technological advances, partly due to the investment in traditional watchmaking.

Greubel Forsey GMT Quadruple Tourbillon Technical Specifications

Unique edition of 66 pieces, 11 pieces in white gold
Hand-wound movement with 3 patents
GMT • 2nd time zone • rotating globe with universal time and day-and-night • universal time on 24 time zones • cities observing summer time • lateral window showing the equator and southern hemisphere • GMT pusher • Quadruple Tourbillon • hours and minutes • small seconds • power-reserve

Movement

Movement dimensions

Diameter : 39.50 mm
Thickness : 13.00 mm

Number of parts

Movement : 705 parts
Four tourbillon cages : 260 parts
Total weight of the cages : 2.25 g
Spherical differential : 28 parts

Number of jewels

84
Olived-domed jewels in gold chatons

Chronometric power reserve

72 hours

Barrels

Three 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 white gold mean-time screws (10.70 mm 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, nickel-palladium treatment

Bridges

Nickel silver, frosted and spotted, polished bevelling and countersinks, straight-grained flanks, nickel-palladium treatment
Gold plate engraved with the individual number
Flat black polished gold plates with relief engraved text, polished bevelling and countersinks, straight-grained flanks
Four flat black polished steel tourbillon bridges, hand-polished bevelling and countersinks, straight-grained flanks

Inner tourbillons

Inclined at a 30° angle, 1 rotation per minute

Outer tourbillons

1 rotation in 4 minutes
Hand-bevelled and open-worked cage pillars
1 gold counterweight per double cage bearing the individual number

Gearing

Involute circle profile
Conical gearing with profiled teeth

Displays

Hours and minutes
Small seconds (mean performance)
72-hours power reserve on a sector
2nd time zone GMT
24 time zones universal time
Rotating titanium globe with universal time
Cities observing summer time
Day-and-night

Exterior

Case

In white gold with asymmetrical convex synthetic sapphire crystal
Transparent back with asymmetrical convex synthetic sapphire crystal
Lateral window with shaped synthetic sapphire crystal
Three-dimensional, variable geometry-shaped lugs
Raised polished engraving “GMT Quadruple” and “Greubel Forsey” on a hand-punched background
Gold security screws
Polished bezel, caseband with hand-finished straight graining
White gold GMT pusher with raised engraving on a handpunched background
Hand-engraved individual number

Case dimensions