Trying to add color to earrings?

[d shiznit]

I've seen and bought at Claire's ball stud earrings that are different colors, like sapphire blue, red, lime green, black, etc. But the thing is, that the coating they used will sometimes fall off and since these kinds of earrings come in sets, I don't have enough of one color. I'm triple pierced and would want three of each color in my ears.

So long question short: If I buy cheap ball studs like in the bottom link, is there a way I can add color to them myself?

http://www.artfire.com/modules.php?name=Shop&op=listing&product_id=1392826