ITEM DETAILS - sizes may vary because its natural gemstones made by nature sizes are around 0.25-0.50 inches (5-8 mm) Amethyst is the world's most popular purple gem. It is the purple color variety of quartz that has been used in personal adornment for over 2000 years. Amethyst is one of the relatively few crystals that can be used with the specific purpose of improving intellectual and cerebral thought. Amethyst boosts hormone production, tunes the endocrine system and metabolism. It strengthens the immune system, reduces pain, and strengthens the body to fight against cancer.