Closely related to the work of the Semon Master, if not actually by the artist himself.
The Semon Master takes his name from an agate scarab in Berlin inscribed HMONOS The form of his letters are Ionic, likely from the Greek Islands. The treatment of the face of this siren, with her long straight nose and full chin, finds close parallels with other gems attributed to this master. Our siren's sickle-shaped wings are identical to those of a sphinx, a figure of Eros, and a bull with human head, all attributed to the Semon Master. The drilled stippling on the siren's body is also found on the body of the sphinx mentioned above. The scaraboid shape and the small hatched border were also favored by this artist.
For the Semon Master, see p. 94ff. in Boardman, Archaic Greek Gems. See also, by the same author, p. 111ff. in "Greek Gem Engravers" in Porada, ed., Ancient Art in Seals, and p. 88 in "Greek Gem Engraving: Archaic to Classical," in Boulter, ed., Greek Art, Archaic into Classical.