Model guide

Vintage Omega Seamaster: how to tell what you've got

"Seamaster" has been on Omega dials since 1948 and covers everything from a 1950s bumper dress watch to a 1970s diver. The name alone tells you almost nothing. The calibre inside and the reference inside the back tell you everything — and both are on this page.

What a vintage Seamaster is

The Seamaster was introduced in 1948 as Omega's water-resistant everyday watch, built on the sealed cases Omega had made for the British forces. It is not one model but a line: through 1975 it ran four generations of movement, was cased in steel, gold cap and solid gold, and split off the Seamaster De Ville (1960–1967, its own page) and the dive watches (Seamaster 300, 120, Ploprof). If your watch says Seamaster and was made before about 1975, it is one of the four generations below.

The four generations, by calibre

The calibre number is stamped on the train wheel bridge, visible with the caseback off. Find it and the era is settled. Dimensions and jewel counts below are from Omega's GF 620 spare-parts catalogues; introduction years from the catalogues where printed and from published references elsewhere.

Dimensions and jewel counts: factory sheet (GF 620-1, 620-3, 620-5). Years: catalogue where printed, otherwise published references.

Case references you will meet

The reference is inside the caseback. Before 1962 it is a plain four-digit number, often with a letter prefix for the metal; from 1962 it is two groups, like 166.010. The prefix is the quickest gold test on the watch: CK and ST are steel, KO is gold cap on steel, OT is 18k gold, KL/KM are gold-cased. This is a working list from the community case register, cross-checked where the factory sheets allow — not every Seamaster ever made.

Reference-to-calibre pairings: community register, checked against Omega's 2012 case sheets where they exist. A pairing not on this list is not wrong — send it and I'll check it.

The 120-metre Seamasters of 1966 to 1979 have their own page: every Seamaster 120 reference, with the calibre inside each one. So do the Seamaster Cosmic and Cosmic 2000.

Have the reference and want the crystal? The crystal lookup reads the same number. Want to know whether the case was built for the movement inside it? That is the question a Movement ID report answers from Omega's own case data.

Dating one

The serial is on the movement, not the case. It is a 7- or 8-digit number engraved on a bridge; put it into the serial number lookup and you get the year band with both published tables shown. As a rule of thumb: bumpers run from about 11 million to 15 million, the 500 series sits around 15–17 million, the 550/560 generation runs roughly 17–29 million, and 1000-series Seamasters start near 29 million. A serial that disagrees with the calibre generation is the first sign of a movement swap.

Is it gold?

Most gold-coloured Seamasters are not solid gold. Omega made the same reference in steel, gold cap and 18k, and the cap versions outnumber the solid ones many times over. The answer is inside the back: a 750 or 585 stamp means solid; no fineness stamp anywhere means capped or plated, however thick the gold looks. A solid 18k Seamaster case with the movement out weighs roughly 20–30 g, which at today's gold price is a four-figure sum on its own; a gold-capped one is worth its case weight in brass. The full test is here, and the weigh-your-Omega tool turns a kitchen-scale reading into an estimate.

Parts for the 565 and the rest of the 55x/56x family: the 565 parts list gives the parts people hunt and which calibres share them.

What it's worth

Every vintage Seamaster is worth three different numbers, and the highest one is not always the whole watch. A 1960s steel automatic with an original dial and the right calibre in the right case sells in the high hundreds to low thousands of dollars. Bumpers with clean dials and the Seamaster 300 references sell well above that. Gold examples carry their metal value as a floor. A redialed, married or heavily polished example drops to parts — a running 552 or 565 movement, a good dial and a correct case sold separately can beat a poor whole watch. The three values, in full.

What goes wrong with them

The three faults that decide a Seamaster's value are all invisible in a listing photo. Redials: the printing is too thick, the minute track is misaligned with the indices, or the word Seamaster sits in the wrong place for the year. Marriages: a 565 in a case Omega built for a 562, or a 1970s movement in a 1960s case — the case reference and the calibre disagree with each other. Over-polishing: the lug edges are soft and the caseback hallmarks are faint, which is when a gold-capped case starts to show brass at the corners. Each of these is checkable, but only from the inside of the watch.

Buying one without getting burned

Most vintage Seamasters change hands on eBay, and eBay is the one place you can see what they actually sold for, not what sellers are asking. The generation table above tells you which one you are looking at; these searches are split the same way.

Ask the seller for these five photos before you pay

• The dial, straight on and under a raking light. Printing crisp, the minute track lined up with the indices, and the word Seamaster where it belongs for the year.
• The caseback, outside and inside. The reference and its prefix: CK or ST is steel, KO is gold cap, OT is 18k. Sold as gold with no 750 or 585 stamp means it isn't solid.
• The movement, with the calibre number readable. A 550 is not a 552, and a 563 is not a 565. Read the bridge, not the listing.
• The lugs from the side. Sharp edges, not polished round. On a gold-capped case, brass at the corners means the cap is through.
• The watch on a kitchen scale. If it is sold as solid gold, the weight has to make sense for the reference.

Questions people ask

How do I tell what year my Omega Seamaster is?

Open the caseback and read the serial engraved on the movement — seven or eight digits — then run it through the serial lookup. The calibre gives a cross-check: bumper calibres are 1948–1955, 500-series 1956–1959, 550/560-series 1958–1969, 1000-series 1969 on.

What movement is in a vintage Omega Seamaster?

One of about twenty, depending on the era — the table above lists them. The number is stamped on the bridge; the calibre lookup gives the full specification for each.

Is my Omega Seamaster solid gold?

Only if there is a fineness stamp (750, 585, 375) inside the back or under the lugs. The case prefix also tells you: OT is 18k, KO is gold cap, CK and ST are steel. No stamp means not solid, however it looks.

How much is a vintage Omega Seamaster worth?

High hundreds to low thousands of dollars for a correct steel automatic; more for bumpers, chronometers, gold and the Seamaster 300; parts value — often a few hundred — for redialed or married examples. It depends on three things you can't see in a photo of the dial, which is what the report is for.

Watch Breaker is an independent identification specialist and parts dealer and is not affiliated with, endorsed by or connected to Omega SA or the Swatch Group. Omega is a trademark of Omega SA. Specifications are transcribed from printed catalogues; reference pairings are community-graded unless stated. Terms.