I'm sensitive to some metals. What are the posts made from? The entire earring, post and all, is made from sterling silver. Relax. It isn't going to rust or turn your skin green.
So what else does the pentacle mean? Oh, so many things! Sometimes, it is a symbol of protection. At other times, it represents the element of Earth, and is linked with prosperity and material wealth. It can also stand for the four elements (Fire, Earth, Air, and Water) working in harmony with the Spirit. In short, there is no short answer!