IWC introduced the Da Vinci Perpetual Calendar reference IW3750-26 in 1985, featuring a polished Red Gold case and a Black dial with contrasting sub dials. This was a groundbreaking development at the time, receiving high praise and causing a stir in the industry due to its price. The popular perpetual calendar mechanism was not only used in the Da Vinci collection, but also in other IWC watches like the Novecento, GST, Pilot’s Chronograph, and even in models by JLC. It was the foundation for IWC's Grande Complication and the impressive Destriero Scafusia. The watch came in a 39mm by 14.3mm case with hinged lugs, available