From a scientific perspective, when a crystal is being formed deep in the layers of the earth, it is heated and compressed which gives off piezoelectric energy.
Piezoelectricity (pee-ay-zo-electricity), is when an electric charge is created or generated on the surface of a solid material causing it to subtly vibrate. It is the same phenomenon in which quartz watches use to keep accurate time.
Everything in this world is made up of electromagnetic energy. We are energetic beings. So by holding a crystal, the crystal begins to vibrate and the energy it creates can transmit and interact with our own energy field.
History: The piezoelectric effect was discovered in 1880 by two French physicists, brothers Pierre and Paul-Jacques Curie, in crystals of quartz and tourmaline. They took the name from the Greek work piezein, which means "to press.”