Onyx is used for the root chakra, as it has incredible grounding and cleansing abilities. Carnelian Red Agate for the sacral chakra because this stone promotes fertility, and boosts desire.
Yellow tigereye was chosen for the solar chakra, because it boosts ambition and heightens intellect.
Rose Quartz for the heart chakra, because it promotes love, compassion and balances emotions.
Amazonite was chosen for the throat chakra because this stone promotes good communication, truth and clarity.
Amethyst is used for the third-eye chakra because it enhances spiritual awareness, and intuition.
Finally Quartz was selected for the crown chakra, because it has the ability to enlighten and lift one to a greater level of consciousness. Quartz is also allochromatic, allowing it to resonate and balance each of the other chakras.