These rings are open in the back so they will fit a variety of sizes. 
These are deep purple amethyst moons.  You can charge these for inspiration, spiritually etc. then you can wear it daily. 
Amethyst
Key words: Protection, purification, spirituality, inspiration,healing
Element:  Water
Planet: Jupiter, Neptune
Amethyst is a member of the quartz family with a trigonal crystal system and a hardness of 7. It’s color ,which varies from pale to deep purple ,is derived from a combination of iron and aluminum.
Amethyst is a beautiful stone for spiritual protection and enlightenment.
It can aid in meditation,helping to still one's thoughts and move into higher states of consciousness. This crystal can clear one’s energy field of negative influences and attachments. Wearing or carrying an amethyst can maintain the inner space of one’s body and energy field in a state of balance and well-being.