Amethyst was thought to control evil thoughts, help sobriety and help overall control of one's thoughts and mindfulness. Helps relieve physical, emotional and psychological pain or stress. Amethyst assists in encouraging our growth towards our higher potential and spiritual expansion. It also brings peace, insight and calmness, and helps insomnia sufferers sleep more easily.
When stones/crystals are carved into a skull, it is to bring the properties of that mineral to you AND your bloodline.