Here’s how you would figure out the right crown for your watch. You are somewhat lucky that your watch has a model name on the dial. Although “Golden Mercury” doesn’t show up on the Omega Database, Google shows a similar watch that was sold some time ago:
https://www.shucktheoyster.com/portfolio/omega-mercury-papillon-solid-gold-1610231-nos/
So now we know the case reference number is 161.023. Next step is to find the part number for the crown that fit this case. One place I like to go is Boley.de. They are a German watch parts supplier with a searchable database.
If I plug in your case reference, this is what I get.
There is the original Omega part number, LA32006. Unfortunately, that was the part number in the 1960’s when your watch was made. You can run a Google search for that part and you will eventually get to Emmy Watch who will give you the BestFit equivalent part number of 8109-1133Y.
https://www.emmywatch.com/db/part/crown_yellow_la32006--8100-1133y/
Now you have two parts to search for. But wait, there’s more! Omega has totally redone their parts numbering system over the last 60 years. So if you take your watch to an Omega qualified watchmaker, the above two parts numbers may not be helpful. A couple of more Google searches through this forum and others told me that the modern equivalent of this crown is 069SX32006.
I was able to find a U.S. parts supplier that stocks this crown. Not cheap, but available.
https://www.stsupply.com/32006-omega-crown-yellow.html
They use both older part numbers in their description, so I’m pretty comfortable that’s the right one.
However, now you see why it would be easier to find a local watchmaker to sort this for you. They might be sitting on a replacement or have a local supplier that has one.
Good luck, whichever route you choose.
gatorcpa
