The bezel of this ring is engraved with a winged female figure binding her sandal. She is Nike, the goddess of victory. She is usually depicted flying and holding a palm, a crown or a garland of laurels for the winner, but is also is often represented stopping to bind her sandal. The most famous representation of this iconography is the bas-relief on the Temple of Athena Nikè in Athens.
There are many rings bearing figures of Nikè or of her attributes (mainly palms). Some might have been worn by soldiers, to protect them from defeat.
The gold plug is certainly more than a decorative element. It presumably had a magical significance as a symbol of the sun, wisdom or healing qualities.