Green Skin issues?
Any jewelry with some copper content can react with your body's ph levels and leave a harmless discoloration where the jewelry rests on your skin. This is even true of certain gold alloys, particularly rose gold as it gets it's pink hue from a high concentration of copper in the alloy.
Want to learn more about green skin and jewelry? Read this excellent article on the subject.
But there is a way to prevent this leaching of copper salts into the skin. Putting a barrier between the metal and your skin will eliminate the greening. I'm sure you've heard of using clear nail polish to coat the inside of your item. And while this does work, nail polish wears off very quickly. So, I'm going to recommend a different product that was designed to be used on all kinds of metals that lasts much longer than nail polish.
If you follow the application instructions exactly you'll get a year or more of protection on items you wear occasionally OR 3-4 months of protection on items you wear all the time.
There are other products out there but this is the one that has given me the best results over time.