Hi Jess
The stones won’t take the heat and you’ve probably burnt the gold backing at the same time that gave them their vibrancy. They’re usually glued in so I’d remove the stones, solder if they are indeed silver and not plated and replace the stones. If they are just plate then there isn’t much you can do.
The heat will also burn off any patina and that would need to be redone using liver of sulphur or platinol reading the safety instructions carefully if you haven’t used it before