I make these studs from scraps of brass and copper pipes. I cut the pipes open, roll them flat, cut the circles, and solder sterling silver earring backs to the pieces so that your ears are touching sterling instead of the brass and copper.
I take care to preserve the original texture of the brass and copper, often marked made by the flow of water through the pipe over time. Each pair of studs is totally unique! The earrings vary from simple satin finishes to rough, moon-like markings.