And on the dial side?

"The front dial of the Ref. 6002 is a work of art in its own right. Its small surface unites the skills of many specialists who master milling, applique setting, and – most spectacularly – enameling with the champlevé and cloisonné techniques.

The dial is crafted from a thin disk in gold that is milled out until the crisp railway track scale, the surrounds of the dial center, calendar apertures, and moon-phase display stand out in relief. This is followed by the work of the specialized champlevé enameler who fills the recesses around the relief contours with molten enamel by hand. The viscous mixture of vitreous powder, metal oxides for color, and oil is applied with an ultra-fine brush. Even the smallest bounded recesses are carefully filled with enamel. When all recesses have been uniformly filled, the miniature oeuvre is fired in the oven at 850° Celsius.

Conversely, the center of the dial is decorated with so-called cloisonné enamel. This technique involves shaping the contours of the blossoms and leaves using fine, flattened gold wire that must be affixed to the dial. The result of countless hours of painstaking work is numerous separate cells (cloisons) that are then filled with enamel of different shades of blue. Again, the next step is firing and fusing for eternity in an oven at about 850° Celsius.

While most contours in the form of silvery relief structures are embedded in blue enamel, the Roman hour numerals are gold appliques. Other dial elements such as the numerals and the markers of the retrograde calendar scale, the PATEK PHILIPPE GENEVE and TOURBILLON inscriptions, the movement number and the delicately pointed stars are painted bright gray.

The small lunar disk is another fine example of champlevé: the circumference of the moon is elaborated in relief and enclosed with blue enamel. The cratered landscape of the moon’s surface is emulated with gradations of white, gray, and black enamel. This represents a huge effort for a single dial element, but it certainly ranks among the most poetic complications imaginable. For a watch of the likes of the Sky Moon Tourbillon, no amount of work can be deemed unreasonable when the issue is to pay tribute to the movement that ticks beneath the phenomenal dial."