This crystal is Amethyst. Amethyst is the stone of spiritual protection and purification. It is said to create a "Shield of Spiritual Light" around the body. Carry this crystal to protect from low energies, stress and unhealthy environments.
These Tumbled Amethyst Crystals are about 1-1/4" tall and 1" wide for the medium sized crystals. For the small size they are about 1" long and about 3/4" wide. For the extra small size they are about 3/4" long and about 1/2" wide.