Copper is rumoured to have healing properties and is often worn by people with arthritis to ease achey joints. Copper is also the traditional gift given to celebrate the 7th wedding anniversay.
The skin of some people may turn a greenish colour when their copper jewelry is worn snugly against the skin (as with some cuffs or rings). This coloration is not harmful and is easily removed with soap and water.
Your copper jewelry has been oxidized with a 'liver of sulfur' solution to give it an antiqued finish or patina. It has been coated with Renaissance Wax ("jeweler's wax) to preserve the patina, but it will naturally darken with age in the presence of air.
To clean and brighten your copper jewelry you can soak it in ketchup for 2-3 minutes and then rinse it well with water using an old toothbrush. Dry with a soft cloth. To reduce the darkening process it is recommended that you store your copper jewelry pieces in a ziplock bag to keep air out as much as possible.