Uncertain, circa 10th century. Medallion (Bronze, 23 mm, 4.46 g, 6 h), perhaps part of a bracelet or necklace. IC-XC/NHKA ('May Jesus Christ conquer') Large Greek cross. Rev. +ΘE R/OHΘH T/H CH ΔO/ΛH ('Mother of God, help your servant'). Very fine.
The invocation uses the female form of 'servant', indicating that this piece of jewelry belonged to a pious Byzantine woman.