SIHH 2018: Greubel Forsey Différentiel d’Égalité, GMT Earth and Double Balancier Watches

By Carl Scutt

This year’s SIHH promises to be a good year for everyone if the new releases are anything to go by. This year Greubel Forsey is releasing three new models to their collection, although only one is a totally new model.

The Collection

The three offerings are the Différentiel d’Égalité,  GMT Earth, and the Double Balancier, the Différentiel d’Égalité being the new arrival rather that an updated incarnation.

Let’s start with the new entry, the shiny new Différentiel d’Égalité that boasts as its crowning glory the Robert Greubel and Stephen Forsey’s 5th Invention.

Différentiel d’Égalité

Don’t worry, you can be forgiven for asking “what the heck is that?” They is a story to it and goes something like this;

In 2008 in a universe far far away Greubel Forsey introduced to the world ‘via Baselworld’ a new and better balance wheel offering a steady rate of energy transfer from the mainspring. That’s good news I hear you shouting… Well, yes, of course, all improvements are welcome, but what does it all mean?

Basically, the 5th Invention achieved its task by having a secondary spring on the differential. This secondary spring was able to reset itself every 5 seconds helping to regulate a constant rate of energy transfer.

So What’s New?

At the time this was more a proof of concept than a working implementation, but now, after all this time the 5th Invention has been improved, refined, and produced, to offers mechanism that resets itself every second to maintain regular energy transfer. Not only that, the Différentiel d’Égalité features the Greubel Forsey’s 30° inclined balance wheel. This allows the mechanism to stop and the second hand set to zero when the crown is pulled out, meaning greater accuracy.

GMT Earth

If you’re familiar with the previous incarnation you may be asking what’s new here? The answer lies in the design of the 3D globe at 7 o clock. In the new model the glode is now more visible. Previously, the globe rotated every 24 hours with only the northern half being in view. Now with the introduction of sapphire glass, the entire globe is visible from front, back and the side.

All the other feature you’re familiar with are the same, the hours, minutes, small seconds, 72-hour power reserve indicator remain the same. The GMT time indicator and the 24-time zone universal time indicator are visible through the caseback, and the watch retains its 24-second tourbillon reclined at 25°.

Double Balancier

First seen at SIHH 2016 the Double Balancier is a lovely piece that was first introduced in white gold and silvered gold dial.  This year it’s been revamped in a 43mm 5N red gold case featuring multi-layered gold dial in black, with engraved and oven-fired enameled indexes.


The Greubel Forsey Différentiel d’Égalité will be produced in a 44mm white gold case, limited to 33 pieces. Likewise, the Greubel Forsey GMT Earth and Double Balancier will be limited to 33 pieces,  the GMT Earth produced in a 45.5mm white gold case.

Final Word

It’s always difficult to find fault in timepieces that have be labored over and have proved themselves over time. However, if I had to choose a favorite from this collection it would be the GMT Earth. Okay, so it’s a little bit ‘in your face’ but I really like the visible globe, and it just comes across as good fun just as much as well built.