In bringing the Quadruple Tourbillon and the GMT mechanisms together, Greubel Forsey not only accomplished a major technical feat that led to the creation of a new hand-wound calibre comprising 705 parts, including three fast-rotating barrels. The Inventor Watchmakers also tackled this challenge from an architectural angle to create a timepiece in which the three-dimensional approach is expressed on many levels.
The main hours/minutes dial between 1 and 2 o’clock forms the highest point of the dial, where it is underlined by the subtle asymmetry of the case and complemented by a 72-hour chronometric power-reserve display. The next level is it at 4 o’clock, with the coaxial small seconds and second time zone display adjustable in one-hour increments by means of a pusher. Between 8 and 9 o’clock, observers can admire the spectacular sight of the Earth in motion, surrounded by a fixed 24 hours ring around the Equator and displaying local time for all the longitudes – simultaneously taking account of the day/night indicator.
Universal time is visible through the case back, with a fixed 24-hour scale bearing day/night zones and a disk with three-letter abbreviations of 24 cities representing the various time zones. This disk also distinguishes between the time zones that implement Summer Time (Daylight Saving Time) appearing in a light colour; and those that do not (shown on a dark backdrop).
The case back also provides a chance to admire the Quadruple Tourbillon as well as frosted bridges with jewels set in gold chatons. The two complex asymmetrical convex sapphire crystals protecting the dial and case back also called for the utmost expertise.