Need help with stamp in possible gold case

That is likely coin silver. Coin silver is ordinarily between .800 and .900 fine. Depending on the origin of the maker. I suspect your case is of European origin as I see parts of the finish are gold plated. This fashion of gold plating on silver watch cases is called “gallone”. If you look for the definition of gallone, it is usually defined as gold braid on a military uniform. You don’t show an image of marks inside the case back, but if there are stampings, more may be discovered.