A: Uterus with a five-bitted key. Inscription around, beginning at top left: νωβτκιρεποοω → unidentified voces.
B: Inscription in three lines: ιαω|νωβτκ|ιρεπο → voces including Ἰάω.
Perhaps post-antique?
Bibliography
Michel, BM on CBd-733
The British Museum Collection database on CBd-733
Images
Cast of CBd-733 in the Gems Database of the Beazley Archive, Oxford