Greubel Forsey Caliber GF02N

Manufacturer	Greubel Forsey
Caliber Number	GF02N
In-House?	Yes
Movement Type	Manual-wind, mechanical, tourbillon
Jewels	38
Total Parts	338
Beat Rate	21,600 bph
Power Reserve	72 hours
Barrel Count	2
Escapement	Lever style
Balance	Free sprung, variable interia with gold screws
Hand Count	6
Functions	Offset hours and minutes indicator between 6:00 and 9:00; small seconds subdial at 11:00; power reserve indicator between 12:00 and 3:00
Features	Patented 30 degree double tourbillon
Finishing	Frosted nickel silver bridges; hand-polished wheels, screws, countersinks, etc.; gold jewel chatons; hand-beveled edges; black polishing; hand-hammered bas-relief
Country of Manufacture	Switzerland, Swiss made
Known Models	Greubel Forsey Invention Piece 1

The Greubel Forsey caliber GF02N is a manual-wind double tourbillon movement found in the award-winning Greubel Forsey Invention 1 watch.

Double Tourbillon 30°:

The GN02N features the brand’s inventive Double Tourbillon 30° complication. It is called “30 degrees” because of the 30-degree angle separating the two tourbillon cages.

Together, the double cage is constructed of 128 parts that weigh in at a mere 1.17 grams.

One the outside is a 4 minute tourbillon with a 60 seconds tourbillon within. The goal of this double setup is to improve accuracy while more efficiently handling constant movement by the watch wearer.

In the brand’s own words:

“Invention Piece 1 Double Tourbillon 30° It took us four years of research and development to realise our first invention, the Double Tourbillon 30°, which features an innovative double tourbillon mechanism with one tourbillon – inclined at 30° and rotating in 60 seconds – inside another rotating in four minutes. The combination of the 30° inclination with the different rotational speeds of the two tourbillons improves timekeeping by averaging out positional errors due to gravity, especially in stable positions.” -Grebuel Forsey

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Note: This caliber listing is still being updated, but feel free to start discussions on it in the comments below…