Help identifying a Seamaster De Ville

Hi,

This is the watch my dad has worn daily since the mid 80s, when he bought it secondhand from a friend.

We don’t know exactly what model it is, how old it is or whether it’s gold filled/plated/solid. It looks like there might be hallmarks/stampings on the lugs but I can’t read them, even under a loupe.

I don’t have the ability to open the case at the moment, and these are just a couple of quick (terribly taken, for which I apologise) snaps taken while he was visiting.

Looks like it could be a 166.020 in 18k gold

yeah, if it was gold plated then the case back would be steel.

Gold-plated model will have steel caseback, but gold filled will have gold filled caseback as far as I remember. But with hallmarks on the lug like this, 90% this is a solid gold case.

Thank you! Thats really helpful.