Nivada Grenchen Chronomaster Aviator Sea Diver 85017 / 4531

The Ref. 85017 represents the functional peak of the manual-wind Chronomaster series from the mid-1970s. Its defining feature is the use of the Valjoux 7736 movement, a significant upgrade that introduced a third chronograph register for tracking up to 12 hours. This transformed the Chronomaster from a short-interval timer into a long-event chronograph, greatly enhancing its utility. The watch is housed in the larger 39mm tonneau-style “C-case” characteristic of the 1970s, giving it a substantial wrist presence. The dial was redesigned to a classic 6-9-12 layout to accommodate the new 12-hour counter at the 6 o’clock position, the running seconds at 9, and the 30-minute counter at 3. These models often carried over the bold aesthetic of the era, frequently featuring bright orange or red hands and accents. As one of the last manual-wind iterations before the quartz crisis, the Ref. 85017 is a historically important model that combines the popular 70s case design with the most functionally advanced manual caliber used in the Chronomaster’s history.