Mythological Poseidon ring

Mythological Poseidon ring in 18 karat yellow gold. Antique ring featuring the bodies of two mermaids, one representing Poseidon (or Neptune) holding his trident in his left hand and a horn in his right; the other probably depicts Thalassa, divinity of the seas, associated with Thetis and Amphitrite holding an oar in her left hand. Two shells adorn the bezel of the ring, highlighting a large seawater cultured pearl. Antique mythological ring, first part of the 20th century, France.

Eagle head hallmark and partially legible goldsmith's hallmark M.?

Finger size: 56 EU or 7.5 US

Max. ring width: 12 mm

Pearl characteristics (delivered with certificate):

Identification : cultured pearl
Environment: sea water
Treatment: no indication of treatment
Shape: round
Drilling: half-drilled
Dimensions : 7.7 mm
Approximate weight of pearl: 4.07 gr

Note: this jewel is delivered with its LFG (Laboratoire Français de Gemmologie) certificate.
Condition : fine wear scratches

Ring weight: 10.60 gr