Roger Dubuis brings its biretrograde perpetual calendar into a sculptural 40mm Excalibur

The latest Excalibur Biretrograde Perpetual Calendar makes a pointed argument about complicated watchmaking: not every calendar indication needs its own complete circle. Its twin retrograde displays place day and date along curved arcs, leaving the lower dial for an astronomical moon phase.

This is a return to a signature associated with Roger Dubuis himself, reframed by the angular Excalibur case. Instead of a flat classical dial, the display has multiple physical levels, pink-gold structure, blue-toned accents and mother-of-pearl. The arrangement separates everyday information from the more theatrical lunar display.

The appeal of the two arcs is that they immediately signal the beginning and end of each calendar cycle. The trade-off is a busier display than a conventional three-subdial perpetual calendar. The strongest element is the moon-phase disc: its blue aventurine contrasts with the gold and adds a visually distinct focal point.

The manufacturer specifies a 40mm pink-gold case with 100-metre resistance, the automatic RD850 calibre and 60 hours of power reserve. Roger Dubuis claims the moon indication deviates by one day over 122 years, while the perpetual calendar needs no calendar correction until 2100. These are brand claims; Chronolume has not independently tested them.