I have one of these from G.T. (a brand that eventually became Revue Thommen).
Someone messaged me about it wanting to buy one, and I must have deleted the message, but anyway one very similar has come up on Ebay. https://www.ebay.co.uk/itm/166004082892
I have no connection to the seller, just a memory that somebody on here was after one, and this is currently at a very reasonable price and had a recent service.
Interesting.
Is it a frosted crystal over silver? I think that's how it's described. Wonder if you could have the crystal polished (or should have it done).