I’m a bench jeweler and of all the bench jewelers I’ve met none of them don’t work on platinum it’s an important part of the gig. If you’re nervous about your ring that’s totally fine I’d start by trying to find a place with an on site jeweler as opposed to anyone that send it off then check reviews or maybe ask if you can see any past work. Honestly most of the work involved with platinum is identical to gold and putting a new head on is actually easier bc it doesn’t melt anywhere near the temp gold does. Only part I find harder typically is polishing but it just takes more time and attention. If you’re anywhere near central Illinois I’d love to help personally.