Protecting Against Jewelry Stains?

I recently got the Kitty Ear White Bondage Set and it has a lock on it that I have been told can stain my girl. Of course it's the hot humid time of year for us which will cause it to stain. I'd like to avoid getting a stain as my girl really enjoys wearing this outfit. So the thought came to me, can I coat the lock in something to protect my little girl? Has anyone tried using clear nail polish or a clear coat paint on this little cast metal jewelry items to seal them in and prevent them from staining the girls' skin? What do you all think?

I've used clear nail polish on similar things and never had an issue once I used it so I'd say do that. Just try not to get the nail polish on the clothes lol.

Glad to know someone else has tried it. I'd take it off before I coated it as I only need to coat the lock. The little ring doesn't come near her skin, so I don't need to worry about cracking the coating as I bend it. But now I need to go buy some clear nail polish. My wife actually had some, but who knows how long it's been since she used it, as it wasn't anywhere near clear now.