Help identifying watch

That looks awfully like the generic Chronographe Suisse style of watch seen with various branding dating from the late ‘40s up until the end of the ‘60s. Despite being marked 18K gold, there is very very little actual gold in them, like 6g at most. The cases are paper thin and very easy to damage. If you pop the back you'll find a base metal inner back and also similar movement ring which adds the strength but of course lowers the gold weight. These were cheap to buy back in the day and were sold as souvenirs to visitors to Switzerland. They trade for low to mid hundreds of pounds/mid to high hundreds of dollars on ebay and the like, though the recent rise in gold prices should put a floor under their values. In theory, a black dial should fetch a higher price, but that one is pretty heavily patinated and the numbers looks to have perhaps been repainted so probably wont attract much of a premium over the other paler versions.

The movement is most likely to be a Landeron 48 or the similar 248