So neither making the colors brighter or darker would help, if I understand you correctly?
I think the simplest solutions for the buttons is to write the color name on the button, or to use a symbol.
Are the colored crystals also a problem? Or anything else?
I was considering to make the new accessory slot only for rings, since I was thinking about the wedding rings when I made this. But the freedom to use any possible combination seemed like the better choice, so you can freely use both accessory slots for everything.