Description

Greubel Forsey's milestone achievement was enabled by a series of layered timing refinements. The first and foremost innovation was in the name: Double Tourbillon 30°. Unlike conventional wristwatch tourbillon regulators, the Greubel Forsey design ensures that gravity’s effect on watch timing is minimized regardless of how the watch is worn.

Greubel and Forsey’s 30-degree inclined tourbillon rotates in one-minute circuits to ensure the hairspring cycles through its gravity-induced fast and slow breathing in equal amounts of time. A second tourbillon making one circuit every four minutes spins the balance assembly on a different axis than the inner cage. As a result, whether on the wrist or stationary on a dresser through the night, the Double Tourbillon 30° functions somewhat like a pocket watch tourbillon.

Additional refinements include a free-sprung balance adjusted in six positions, a Phillips overcoil for the hairspring, a full bridge to better brace the tourbillon against shock, and twin mainspring barrels operating in series to apply a flatter torque curve to the operation of the escapement.

Every screw retaining the parts of this caliber is black polished on its top and chamfered down its slot and around its circumference. A fired-blue steel wheel with four serpentine arms acts as the running seconds indicator for the four-minute tourbillon.

On the back, Greubel Forsey earns its reputation for best-in-the-business detail. Caliber GF02 is calculated to evoke vintage La Chaux-de-Fond pocket watch design, but the execution surpasses antiquity’s best efforts. The bridges and plates are constructed of maillechort, a nickel-copper-zinc alloy often called German silver. Greubel Forsey employs its unique “jade gold” gilding to create an even warmer effect. All bridges are frosted, and the base plate of the movement bears satin concentric grain from engine turning.