IWC 18k yellow gold chronograph Da Vinci

IWC fine, astronomical 18k yellow gold chronograph with perpetual calendar model Da Vinci reference 3750, self winding, Switzerland around 1985, solid gold case including leather strap with original 18k yellow gold buckle, snap on case back, screwed down winding crown, movable lugs, enamel colored dial with raised hour-signs, display of hours, minutes, constant second, perpetual calendar (day, date, month, year & moon phase)& chronograph, gold-plated movement finely refined, 36 jewels, calibre 79061, blued screws, central rotor, diameter approx. 39 mm, signs of use due to age, condition 2-3, discontinued model, from the estate of a collector