The theory concerning the use of Crystals and Gemstones is that they carry vibrations from the energy of the earth. By putting these crystals on the "Chakras" within your aura, your aura's vibrations change.
Sometimes after a healing session with Crystals the person might not feel any change at all, as it may well be subtle over a period of time, for other people the effects are very direct and immediate.
Before I go any further, I need to explain about the "Chakras". There are many "Chakras" in the body, but the main ones used are the seven principal ones that run from the head to base of spine.
The first one is the "Base Chakra" which is red in colour. Here we cram everything in life that has happened to us whether good or bad. The parts of the body covered include the perineum, the point between the anus and in addition the sex organs. We need to clear this "Chakra" out many times to save ourselves back problems or other illnesses.
Next to the, "Sacral Chakra", centre of the abdomen and normally orange in colour. This represents the reproductive system, sexual organs and lumbar plexus. We need to keep this "Chakra" unblocked as it can also help us maintain well being of the body.
The middle one as I call it is the "Solar plexus Chakra", usually yellow in colour. The parts of the body associated with this "Chakra" include the muscular system, the skin as a system, the solar plexus, the large intestine, stomach, liver, and other organs and glands in the region of the solar plexus. Also the eyes, as the organs of sight, and the face, representing figuratively the face one shows the world. Also we pack our emotions here at the solar plexus, our worries and fears hence the saying "butterflies in the stomach", or experiencing that churning feeling in the stomach.