Wrong Color Rune?

Considering the difficulty finding runes of a specific color - what happens when you power up your talisman with a different color rune?

The talisman stats increase no matter what the color.

I thought I read something somewhere about "experience", but if that's simply extra experience points that level a character, I'd rather miss out and simply boost my talisman with a different color.

I'm probably missing something here - anyone care to shed some light?

Thanks!

you use more resources if you use the wrong color. example - for powering up a green talisman using a green rune it might cost 10 runes and 5000 gold. doing the same thing with a red rune might look like 15 runes and 10000 gold. cheers