We need a soft brush, plenty of baking soda, a small pot, and a little water. You must rub the baking soda on the jewelry, for a few minutes with a soft brush, it can be a toothbrush, when the baking soda turns from white to gray, put the jewelry in a small pot with more bicarbonate, let it work for a few hours and finally add hot water and dry it. Your jewelry will be as good as new!