The name Michael means "He who is like God". His aura is said to be of royal blue, with tinges of royal purple. The crystal Sugilite would be the crystal that best matches his frequency. He is the archangel of faith and protection, of purpose, love, and power; of overcoming worries, lower emotions and one's lower nature.
He is the general of the heavenly troops.
"The Angelic Being, referred to as the prince of heavenly hosts who is the defender and protector of faith. He is commander of the celestial army, and uses the sword of blue flame to vanquish the forces of darkness.
[From Hebrew: he who is like God.]" (SJA)