OMEGA Constellation 131.30.41.21.04.001: specs and what to check

Three millimetres of overhang

The two published figures that matter most here sit unusually close together.

Case diameter: 41 mm. Lug to lug: 44.00 mm.

Three millimetres of total overhang — a millimetre and a half at each end. For comparison, most of the watches documented on this site run six to ten millimetres longer than they are wide, and the Speedmaster '57 at 40.5 mm spans nearly fifty.

That is the single most useful thing you can tell a buyer about this reference. It is a 41 mm watch that behaves on the wrist like something considerably smaller, because there is almost nothing extending past the case.

Quote both numbers together. Diameter alone makes it sound like a large watch; the pair together describe what actually turns up.

A measurement the maker does not give

OMEGA publishes a between lugs figure for nearly every other reference documented here. Not this one.

The reason is visible in the case design — the bracelet integrates into the case rather than sitting between conventional lugs — but the reason is not the point. The point is that the figure is absent, and a dealer should not manufacture one.

If a buyer asks, measure the watch in front of you and tell them what you measured. If you are sourcing any hardware, measure first rather than ordering from a number you found somewhere.

Saying "OMEGA does not publish this" is a stronger position than producing a figure you cannot stand behind.

White is a colour that depends on your lamp

The dial is listed simply as white.

White is deceptively hard to photograph honestly. Under warm domestic light it records as cream; under fluorescent it goes faintly green; under a phone camera's automatic correction it can come back grey. A buyer who sees a warm dial in your pictures will suspect the dial has aged, and a buyer who sees a cold one will find the real watch disappointing.

Look at it in daylight and in artificial light yourself before writing a word about colour. Then lock the camera's white balance, include a grey reference in at least one shot, and let the buyer judge your lighting for themselves.

A hidden clasp under 171 grams

The closure is a foldover butterfly clasp with comfort setting, and the complete watch weighs 171 g.

Butterfly clasps disappear into the bracelet, which is the design intent and the inspection problem: nobody ever looks at them, and they take the full load every time the watch goes on or comes off.

Open it a dozen times. Both wings should release with equal pressure and latch positively. Then run the comfort setting out and back through its detents, confirming it holds where you leave it rather than sliding under tension.

Finally, hang the watch from the closed clasp and pull. A hundred and seventy-one grams meeting a hard floor is an expensive noise.

Movement and rating

Calibre 8900, self winding, 60 hours, Master Chronometer certified. 13.50 mm thick, steel case and bracelet, crystal domed sapphire treated on both faces.

Water resistance is 5 bar (50 metres / 165 feet) — hand washing and rain. This is a dress watch and OMEGA describes it as one; there is no reason to borrow vocabulary from the Seamaster catalogue.