A gold cornelian intaglio ouroboros ring

A gold cornelian intaglio ouroboros ring,
possibly Roman, with a carved cornelian intaglio depicting a lady in profile, Roman set in a landscape position, to a domed back setting. An incised snake to each outer edge, with a head to each shoulder, indistinct. Scrolled detail shoulders and a round section shank. Head 15.00 x 12.60mm, 4.00g.
Finger size O approximately, not round