Keep your Copper Jewelry Gleaming by doing this one thing. 

Soak your copper jewelry in a solution of vinegar (a couple of tablespoons), boiling or hot water (enough to cover your pieces), and a teaspoon of table salt, for 10 minutes. Then rinse your jewelry with cold water and dry with a soft cloth. 

Tip: Vinegar and salt: Rub a mixture of 1 tablespoon of table salt and 1 cup of white vinegar onto the copper with a soft cloth and rinse.

You can also use this method for cleaning your Brass Jewelry.