1930s Omega Cal.23.4SC rare 1st Waterproof with Salmon two-tone roman dial in Staybrite

It uses a valuable early-type waterproof snap-back case distinguished by its caseback that protrudes slightly from the middle case. The caseback is engraved with “MODELE + DEPOSÉ / WATERPROOF,” the same marking found on waterproof cases of the 33.3 chronograph models from the same era.

Although compact at 31mm, the solid construction unique to early waterproof cases gives it a substantial presence that exceeds its size. The preservation is outstanding — the salmon dial retains its beautiful hue and displays an iridescent sheen across the surface.

It houses the Cal. 23.4SC, a center-seconds movement that was rare for its time.