Sterling silver and bronze will naturally tarnish and become darker with time and use. This is a completely natural phenomenon. It is recommended to use a polishing cloth to maintain the shine of both silver and bronze or use the at home technique below. 

To avoid as much tarnishing as possible, store your jewelry in a dry place. While wearing it, avoid moisture (such as swimming, showering, or exercising) and exposure to chemicals (such as perfume, lotion, and cleaning products).

Bronze oxidizes and tarnishes a little faster than silver. For certain people, bronze may cause a greenish mark on the skin depending on individual body chemistry. This is completely normal, harmless, and washes off easily. If this bothers you, applying a thin coat of clear nail polish where the jewelry touches the skin can help prevent this.

How to Clean Your Jewelry at Home

Brush a small amount of toothpaste on the jewelry with a soft toothbrush and cover the entire surface. Let the piece sit for about 10 minutes, rinse well with water, and towel-dry.