The Triple Moon is a symbol of the Goddess in her aspects of the Maiden, Mother, and Crone in the form of the waxing, full, and waning moon.
The Triple Moon symbol is about 3/8" (10 mm) high.
Use the "Customize" option to select the ring size and select and optional symbol for engraving.
See the photos and digital renders for the symbols I can put on the face of the full moon.