Crystals, like earth and metals, transmit energy.
In these studies, we recommend getting a pentagram with the seven metals related to the principal genii and seven alchemical planets of this solar system: silver (Gabriel, the Moon), mercury (Raphael, Mercury), copper (Uriel, Venus), gold (Michael, the Sun), iron (Samael, Mars), tin (Zachariel, Jupiter), and lead (Orifiel, Saturn).
Samael Aun Weor describes how to bless the pentagram in The Major Mysteries and The Gnostic Bible: The Pistis Sophia Unveiled.
This is, in my experience, one of the best forms of protection via a talisman. Crystals are nice and beautiful, but NOTHING like a pentagram of seven metals charged through ritual!
For thirty years I sought God. But when I looked carefully I found that in reality God was the seeker and I the sought. -Bayazid al-Bastami