So I'm looking at my "rock" sections of this backsplash last night, as well as the wooden earrings...

they're dull.

Was thinking about rubbing a tiny bit of (some sort of) oil on them to shine them up.

Or should I use clear nail polish instead? Will that yellow? I don't really care so much on the wood (if it turns yellow) because the wood is very light, and the yellow would likely just make it prettier, BUT I don't want yellow rocks.

Thoughts?