These earrings are made out of reclaimed brass and hang on a sterling silver studs. I do not recommend getting these earrings wet or wearing them during a workout.  I highly recommend getting a metal polish and protectant such as Brasso, Noxon 7, Malco Twinkle, etc. They are inexpensive, very handy (as they polish metals besides brass), and not only clean but also protect your metal from further tarnishing.