Hi and congrats! Funny thing is – this crown looks relatively close to the crowns that were used on steel Monodatics from the 159xxx serial-range. As far as I've seen, there were different variants of crowns used during the Monodatic-dates - some with big ridges like yours, some with smaller ridges (like on the monodate automatics), flat ones for 18 k models, then later signed and flat ones. I believe that gold-plated cases would go with gold-plated crowns. With all this being said – sorry to be of no help 😁 what’s the serial of your watch? I have a little database of monos and could look up which crown style fits according to that (though it’s mostly steel monos).