Clear – Crystal Quartz or Rock Quartz. Combines well with all other crystals and can be used to amplify their energies. It is one of the most popular and versatile healing stones of all the crystals. It is the most powerful healing stone thought to be able to work on any condition. It is known as the stone of power and amplifies any energy or intention. It is said to protects against negativity, connecting you to your higher self and is commonly associated with the CROWN Chakra.