I have a pair of earrings I inherited from my grandmother. I know they're at least 80 years old. They're pendant earrings, set in Austrian crystals, with a screwback holder (not even sure that's what it's called). The screwback is set with larger crystals and marked on the back of the screw is "Japan Silver". I have no idea what this is, I don't even know if it's genuine silver or some other metal.
I searched the internet for a definition and found nothing. Does anyone know what this metal is?