An easy and cheap way to update jewelry is using nailpolish. I have an almost embarrassing amount of nailpolishes in my bathroom (in my defense, I share the collection with my roommate) and therefore it's not hard to find the right color if I want my earrings mint instead of silver.
If you got any kind of necklace, earring or cocktail ring you like the shape of but not so much the color anymore, voila, nailpolish will be your best friend and helper. Above and beyond I've included a couple of pictures of three up my most recent nailpolish updates.
And now: Happy color changing!