Talisman or amulet, a small object intended to bring good luck and/or protection to its owner.
A broad term for an object that is supposed to ward off evil or bring good fortune, including an amulet and a charm, but especially such an object with some astrological or magical symbol. At one time the term was restricted to objects engraved with signs having an astrological significance, as distinguished from amulets bearing occult inscriptions; the Church in the early Christian era permitted generally the latter but condemned the former, although in time amulets and talismans were assimilated.
During the Middle Ages objects of such natures, as well as certain gemstones, were all regarded as talismans.
From: An Illustrated Dictionary of Jewelry, autor: Harold Newman, publishers: Thames and Hudson