In 1985, IWC introduced the Da Vinci Perpetual Calendar, a groundbreaking wristwatch with a perpetual calendar mechanism. It quickly gained recognition and was widely used in other IWC models and even in watches from other brands. The Da Vinci Perpetual 3750 came in a 39mm case with hinged lugs and was available in different metals and dial colors with markings in multiple languages. The default option was plexi glass, but sapphire crystal could be requested. A ceramic version, the 3755, was introduced in 1987 and there was also a gem-set version, the 8153. You could also opt for a bracelet, references 9252 or 9253 for a diamond-set