Diptych of St. Gregory
Monza, Italy, Treasury of the Duomo
The inscription on the left reads DAVID REX, "King David"; on the right, S[AN]C[TU]S GREG[ORIU]S, "Saint Gregory."
Though executed in the 9th century, the diptych appears to be in an earlier style.
More of Saint Gregory
More of King David
Source: Thais – Scultura Italiana