Driven by a spirit of research, Robert Greubel and Stephen Forsey have gone well beyond the conventional Greenwich Mean Time (GMT) display using a window or a hand, by incorporating into their timepiece a terrestrial globe completing each anti-clockwise rotation in 24h - the same direction in which Earth spins.

The GMT calibre is powered by two barrels providing a 72-h power reserve with a frequency of 21,600 vibrations/hour. The calibre comprises 443 components. It features a 24-second tourbillon with 25° inclination, comprising 87 components for a total weight of 0.36g.

Besides its chronometric properties and reliability, this regulator system was adopted for its small size, which meant that a calibre diameter of 36.40 mm (16 ½ lines) could be kept. This makes for a new medium-sized case, 43.5 mm wide with a total height of 16.14 mm.

Made from 950 platinum, it has a slightly lighter hue than the previous white gold version.