A: Horus-Harpocrates sitting to right on lotus with knees drawn up. On both sides of the lotus flower a stalk of grain, under the flower two lotus stalks without buds. Baseline indicating primeval mound? Horus’ left hand raised to his mouth, his right holds a cornucopia. A long side-lock of youth is falling to his neck, on the top of his head a crown. On the right side of the gem a bearded snake facing Horus.
B: ιαω → Ἰάω.
A praxis known from a papyrus (PGM LXI 1-38) specifies that love charms had to be incised with the image of Horus on a lotus flower and the magical name Abraxas. Pieces with the Horus-scheme used as love charms: CBd-533, CBd-534.
S. Michel points to the similarity between the Horus-snake composition on the gem and Egyptian decan-representations (see link below).
Bibliography
Michel, BM on CBd-507
The British Museum Collection database on CBd-507