This is a Beautiful Deep Purple Natural Amethyst Crystal Gem Polished Ring.
 
Amethyst, can beanywhere between deep and light purple in colour of quartz.
It is deeply connected to spirituality, often associated with calmness, wisdom, and spiritual healing.  It's believed to enhance spiritual awareness, intuition, and psychic abilities by activating the Third Eye and Crown chakras. Its said that Amethyst can also promote inner peace, reduce stress, and protect against negative energy. 
 
It is a size 4 and weights 3.5 grams
 
Comes with a lovely fabric pouch to keep it in.