Omega Seamaster calibre 520

Omegas Seamaster range of watches needs little introduction to anyone with even just a passing interest in vintage wristwatches. Introduced in 1948 to coincide with the brand’s 100th anniversary the line is still being manufactured today, all be it unrecognisable from the first incarnations which were loosely based on watches made for the British military at the end of World War II. This example dates from around the late 1950’s and is a stainless steel cased example.


The watch arrived completely original and in pretty good shape apart from some very delicate lume on the hands and a quite corroded seconds hand. Also, the dial needed a good clean as there was quite a bit of debris on it but thankfully little staining or damage.


With the dial and hands removed the typical Omega gold coloured movement is revealed, which is actually copper electroplated onto the base material.


On the going train side the same finish is used. It’s also apparent that the calibre 520 has an indirectly driven centre seconds hand and swan neck fine adjuster on the regulator.


The watch was stripped for cleaning and inspection and as can be seen the bridle and the end of the mainspring had snapped off.


Typically this means the watches power reserve will be severely depleted as the mainspring can’t locate in the recess on the barrel wall, and will just slip as the watch is wound.


The components were treated to a spin in the cleaning machine….


….so I turned my attention to the handset. The seconds hands corrosion was removed and it was given a polish. Genuine new seconds hands are available from the states but they are a horrendous price with the shipping added on and it would be a shame to lose originality on this particular watch. The lume in the hour hand is very thin and fragile and a tiny piece had actually fallen out of the centre, although it’s invisible to the naked eye. Handle with care!


Once the parts were cleaned and inspected it was time for reassembly, a new mainspring was the first component to be fitted.


The motion work was reassembled and lubricated and it sprang into life, the winding mechanism and ratchet wheel has still to be fitted in this picture.


The keyless work was refitted along with the cannon pinion and hour wheel.


Then the cleaned dial and handset was refitted. It was at this point that the lume in the hour hand couldn’t hold on any longer and dropped out as I refitted it to its pinion.


Normally this would be the point where a relume would be considered, however given the originality of this watch it seemed a shame to remove the lume from both hands and indicies just because of a frustrating, but small loss on the hour hand. After all, it’s only original once! It was decided to repair the missing area, so a batch of binder was tinted to as good a match as I could manage and the missing fragments that I’d collected were powdered and mixed into the batch.


It turned out quite well al things considered, not invisible under high magnification but hardly noticeable on the wrist. I much prefer to conserve rather than replace compenents wherever possible.


A shot of the caseback, it’s interesting to note that it has two models listed inside, the 2694 and 2970 which meant the caseback was used on two different models. The twin numbers were due to rationalisation in the Omega factory, rather than having two separate stocks of casebacks each with a different model number, there was just one stock with both numbers present. This appears on quite a few casebacks of the era that were interchangeable with different models.


A shot of the beautiful calibre 520 movement, now cased back up.


Omegas Hippocampus logo is featured on the outside of the caseback.


And the finished watch is still completely original – apart from the mainspring and a small amount of lume binder! Even the (polished) crystal still has the original Omega symbol visible in the centre, it’s faint but it’s there.





  1. Hello, really fascinating article as I’m looking to buy one of these! So I know I’m not being ripped off, what would an all original 1960s Omega Seamaster calibre 520 be worth? In good condition.


    1. The value of these right now seems to be anything from £300 to £800 for a good stainless steel model. Type of dial, handset and above all condition are the deciding factors, if it has a desirable dial and handset in great condition you’d be looking at the top end of the scale.


  2. Hi I have a very similar watch – it has a much thinner crown which I suspect is not original and hard to wind. Is it straightforward to find an original crown?


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