Varnish.

Recently, I put a sticker in the shape of a heart on my shoulder and ended up sunburned like that.

I was thinking.

What if you could do that with violin varnish?

You could put an itty-bitty heart on the back, in perhaps the corner, and stain everywhere but the heart, getting as close as possible, leave it on while it dries, and clear coat polish over it.

Just a thought.