Articles of jewelry which, during the Middle Ages and later, were regarded, by belief or superstition, as having magical or medicinal powers, and so were worn for other than ornamental or sentimental reasons. Early forms were the amulet, bulla or finger ring bearing an astrological, magical or religious inscription, word or symbol, or set with a scarab or a magical stone.
A later example was the reliquary, as well as certain articles of devotional jewelry that sought the intercession of a saint. Some articles were supposed to have magical powers from extrinsic circumstances of their creation, e.g. the cramp ring or touchpiece.
From: An Illustrated Dictionary of Jewelry, autor: Harold Newman, publishers: Thames and Hudson