After the 31st day of the month, the retrograde date display of the Portugieser Tourbillon Mystère Rétrograde automatically jumps back to the 1st; in shorter months, the hand can be directly advanced using a rapid-advance system until it reverts to the 1st. The 7-day power reserve display indicates how much energy remains in the IWC-manufactured 51900 calibre. For watch lovers, one of the most fascinating aspects of this model is the unusual presentation of the flying tourbillon, consisting…