Delicate and complex, the openworked structure of the large 1966 watch movement with automatic winding, measuring 13¼ lignes (30.00 mm), invites contemplation of its bridges and plates. In this exposed millimetric design, gears, levers, bolts and other usually invisible components can be glimpsed within the openings – chamfered, polished, satin-brushed and hand-finished by the watch artisans. Their expertise has enabled them to push back the structural limits of the material and infuse it with a sublime character by skeletonizing the mechanics, the leaf-shaped hands of which are, along with the balance wheel judiciously placed at 12 o’clock, the defining graphic feature.
This movement, derived from the famous GP1800 calibre, is treated using a galvanic process (anthracite grey ruthenium) and worked like a metal net. It enables the eye to follow the movement of energy thanks to the rhodium-plated gear train. During this voyage of discovery into the heart of a mechanical labyrinth comprising 173 components, including 25 jewels, the eyes come to rest on the sweep seconds at 10 o’clock carried by the seconds wheel. They are then in turn captivated by the quick oscillations of the regulating organ featuring a “Microvar” variable inertia balance exclusive to Girard-Perregaux, pulsating at 4 Hz (28,800 vibrations per hour).
To further enhance this 13¼ lignes calibre within the 38 mm diameter, 18k pink gold case, Girard-Perregaux chose to skeletonize the oscillating weight which, visible through the sapphire crystal case back, has been crafted in gold. Magnificently balanced, this rotor ensures optimal winding of the barrel destined to guarantee autonomy of more than 54 hours.