Metal hypersensitivity, also called allergic contact dermatitis, is one of the most common types of skin allergies and affects 10% to 15% of the US population. Look for hypoallergenic jewelry since they are less likely to cause an allergic reaction.
Humans have long since been fascinated by pearls, and mollusks have produced them throughout evolutionary history. Romans thought they were frozen tears of the Gods, Greeks attributed them to lightning strikes at sea. They were commonly dedicated to Venus, Goddess of love & beauty. Alexander Severus, born in Africa and not to be confused with Severus Snape from Harry Potter, reportedly hung pearls in the ears of a status of Venus. They're known as the Queen of Gems... but what causes a pearl?
What exactly is a bead? One definition offered by Merriam Webster is "a small piece of material pierced for threading on a string or wire (as in a rosary)." Throughout history, they've been used for spiritual/devotional purposes, as worry beads, gaming beads, for medicinal purposes, and as a form of currency. They're considered to be one of the oldest forms of trade in history.