Moonwatch 3861 Sapphire

The sapphire Speedmaster Professional is the 2021-generation Moonwatch with a window on both sides. At the front is the familiar black stopwatch dial; at the back is the hand-wound calibre 3861. It shares its 42 mm steel case and basic mechanism with the acrylic-fronted version, but makes different decisions about what the owner can see.

The watch tells the time with two main hands and a small running-seconds display at nine. Its long central hand belongs to the stopwatch, with separate counters for elapsed minutes and hours. That arrangement descends from the Speedmaster introduced in 1957, before NASA adopted the watch. The modern version keeps the old layout without keeping the old movement.

Through the sapphire back, the 3861's wheels, bridges and stopwatch mechanism are visible. There is no large automatic winding weight moving over them: the owner winds the spring by turning the crown. The Co-Axial escapement and resistance to strong magnetic fields are among the changes behind its modern Master Chronometer certification.

The front has distinctions of its own. Its sapphire cover resists scratches better than acrylic. An applied metal Omega emblem rises above the dial, where the acrylic version uses a printed logo. The black face steps down at the outer minute track, and the aluminium timing ring places its dot above ninety in a deliberate return to an early detail. Polished elements within the steel bracelet add another difference from the more uniformly brushed acrylic version.