Crosses similar to this one are found in all media throughout the Byzantine world.
As Christianity became the dominant religion in Byzantine society, Christian imagery was increasingly found on jewelry. Crosses appear by the fifth century; the Virgin Mary, saints, angels, and other holy figures became popular in the sixth century. The images were thought to protect the wearer, aid in prayers, and even perform miracles.
J. Pierpont Morgan, London and New York (until 1917)