Help identifying a commemorative Omega watch

Hi everyone! First time posting here. I'm not a watch enthusiast or expert of any sort, but my mother recently stumbled upon a family watch that I'm trying to identify.

The watch is an Omega my grandfather received during his police service at Quirinale (the Italian President's headquarters). It also has the President's signature on the back, Antonio Segni, that was in charge between 1962 and 1964.

I tried to do some online research but i can't find anything about this specific model. I hope this community can help me solve this mystery!

Thanks! I'll have it opened by a professional watchmaker and post any finding

So i went to a watchmaker and took pictures of the interior.
The model is 121.002-63 and the case is gold plated, meaning that it doesn't have any particular economic value.
Case closed (no pun intended) 😎