The new IWC-manufactured 89630 calibre in the Da Vinci Perpetual Calendar Chronograph is the first from IWC to combine the double chronograph counter with Kurt Klaus’s moon phase system and place them both on a subdial.
- The moon itself is just three millimetres and remains stationary against the night sky while the moon phase disc below the dial, acting as a shadow of the earth, depicts the waxing and waning moon.
- The perpetual calendar functions with the same precision as in the Portugieser Perpetual Calendar: in 577.5 years, the display will diverge by just one day from the moon’s actual course.
For the chronograph, the design engineers likewise made no concessions. The hour and minute counters are combined in a totalizer at “12 o’clock”, which enables stopped times to be read off as if they were the time of day. Stopped times are shown to an accuracy of a quarter of a second by the central blue chronograph seconds hand. The flyback function enables the chronograph to exit a current measurement instantaneously, without an in termediate stop, and to start a new one immediately. In the red gold model, the Reference IW392101, the case, lugs, crown and push buttons are made of solid 18-carat red gold. The dark brown alligator leather strap by Santoni is likewise fastened securely to the wrist by a folding clasp in gold. In the stain less-steel Reference IW392103 with its black leather strap by Santoni, the slate-coloured sub dials are covered with a thin coating of rhodium, which gives them a distinctive cool and silvery appearance. The Da Vinci Perpetual Calendar Chrono graph has an impressive case diameter of 43 millimetres, an equally striking case height of 15.5 millimetres as well as a sapphire-glass back that reveals the complex design of the watch movement with blued screws and unique decorative polishing on the bridges.