Found at the antique mall.
I can’t understand why the case is not marked what it is made of ?
White gold filled ?

 

It looks like steel to me..

 

I suspect it's an electroplated brass case, possibly nickel silver going by the sheen.

White gold would have some form of hallmark.

 

Would be marked acier then ?

 

I’m leaning toward the nickel silver, it is really a nice pocket watch similar to my 18k Patek Philippe !

 

Although the case isn’t marked with the name of the alloy, i think it is a patented alloy called STAYBRITE which was extensively used in the fabrication of many top tier Swiss watch case like Omega and Rolex, and possibly others.

 

Staybrite is a stainless steel alloy developed in the UK, and as you note, used in many Swiss watch cases including Omega.
However, I would expect to see STAYBRITE markings on the caseback as manufacturers were quick to use the markings as a sales pitch.

For example:



I also think this watch may have been made for the French market due to the use of the old "belt/garter" Omega symbol and the "Fabrique en Suisse" marking.

Without having the watch in hand, my comments are just my opinion though.

 

I’ve collected for 40 years, almost all cases say what they are made of ?
Why would Omega do this ?
The watch is fairly solid and heavy Beautiful deco style and etching on the edges ! Very much like my Patek Philippe
with breguet Arabic applied numeral dial hour markers. This had to be a higher end watch at the time ?

 

Can you share a movement picture?

 

Movement picture

 

I second @JimInOz

Usually these unmarked watches have nickelplated cases

 

Very few nickel plated cases for pocket watches. It's either 'métal blanc' i.e. nickel based alloy, or a staybrite produced before Omega advertised them as such inside.
I presume it is a ref CK395, which is contemporary to the first use of Staybrite by Omega around 1934.

 

My sentiments exactly. The colour does not appear to me to be typical of a chrome plated case. It looks to me much more like Staybrite alloy than a chrome plated base metal case.

 

Hello again,
I checked the similar watch I have. It is not a ref 395 (the OP watch has an hinge, ref 395 doesn't). I don't know the exact ref for this model.
Here are pictures (dial is different than the OP's watch but we know Omega used a variety of different dials on the same references) It all the same color as the bow, the reflection of the brown support tainted the color :


Caliber 35.5L T1 inside :

Nothing engraved about the metal used for the case but I am pretty sure it is nickel (too shiny and warmer color than staybrite) :


For comparison, here is a ref CK395, nearly the same case design but thinner bezel, no hinge, caliber 37.6 inside, made of stainless steel and marked as such :