Copper and Bronze jewelry all have potential to turn skin green temporarily! Not everyone is effected, but its a result of oxidation. The only way to stop this is to keep the jewelry coated, I personally recommend ceramic based protectants they last the longest and don't change the look of the ring! Another cheap option is to put clear nail polish on the jewelry, it's completely up to customers preference. But each ring comes with high grade nano-cermamic coating.