It should also be known, according to my last experience, that this is only done in Switzerland, so your watch would be gone for some time. I had this done in 2017 on a 127, even though I was 90% sure it was authentic, I could not trace it to the original buyer, so I sent it off. They returned it with a certificate. I also had a full service while it was out. While it did take several months, my experience was excellent, and the piece of mind was worth the effort, to me!
There are some amazing fakes out there. Be careful!
This was done through the Beverly HIlls Boutique, and as always, they're awesome (so is Bal Harbour in Florida).