Geneva Seal engraved on Movement. Hidden Tourbillon. Truly awe-inspiring piece that is almost impossible to find. Poire hands. Month at 3 o'clock, moonphase at 6 o'clock, leap year cycle at 12 o'clock. Retrograde (jumps-back) center date hand. On the back celestial sky dial, the white skeletonized hands indicate the sidereal hour as it occurs every 23 hours, 56 minutes and 4.1 seconds. The eliptical sky vault displays the present orientation of the visible celestial sky. The lunar cycle of 29 days, 12 hours, 44 minutes and 2.82 seconds is also indicated on the rear dial. This watch would be the crown-jewel in any afficionados collection, other than perhaps, the Vacheron Constantin Tour de I'lle. Even more limited than the magnificent Yellow Gold version, the Platinum Sky-Moon Tourbillon is perhaps the rarest continuously produced wristwatch in the world.