I'm not sure about early medieval times.
In the 12th century, european women supposedly didn't wear earrings - this was only something the "strange" saracen (from the east) women wore (gold hoops set with pearls, etc). This may have been not strictly true, but certainly earrings weren't common on western women at this time (half the western) women were wearing veils which make wearing earrings pretty pointless). I think Saracen men also wore earrings (I'm not sure if in one or both ears).
In the renaisance I see many pictures of men with one large pearl drop earring and women with two.