The pearl is the oldest known gem, and for centuries it was considered the most valuable. A fragment of the oldest known pearl jewelry, found in the sarcophagus of a Persian princess who died in 520 BC, is displayed in the Louvre in Paris. To the ancients, pearls were a symbol of the moon and had magical powers. In classical Rome, only persons above a certain rank were allowed to wear pearl jewelry. Pearls have been considered ideal wedding gifts because they symbolize purity and innocence. In the Hindu religion, the presentation of an undrilled pearl and its piercing has become part of the marriage ceremony.