Short answer: soap suds.
Ours has an E-Coat or is E-Coated with a coat of clear which adds durability and luster to our plated jewelry pieces. So please only use soap suds from handwashing for instance to recharge your jewelry piece's original luster even if the e-coating wears away over time.
DO NOT USE Ammonia nor any kind of Polish nor Abrasive brush.
Don't use a toothbrush nor toothpaste.
Protect the E-Coat and your purchase will last & last.
*Reminder - Put on your jewelry AFTER using hairspray, lotions or perfumes, etc.