All the religions of the world mention the use of crystals or gemstones for protection, healing and contemplation, and as being a guide through the development of a person's individuality on a spiritual and material plane.
In every world's nation there has been and still exist experts who know the "secret" relationship between humans and stones whether through scientific methods, or through insight and identification with the matter. The effects and the use of crystals or gemstones are often mentioned in the astrology of the East and the West, and this science connects crystals and gemstones with the influence of planets and stars affecting the whole of living with the spectrum of their radiation. Determining the appropriate crystal or gemstone through the use of Astrology depends on the position of planets at the moment of birth, and if the influence of a certain planet is considered "disturbing", it is recommended that a person wears a certain crystal or gemstone to diminish or neutralize these negative influences.
Astrologers emphasize that since each crystal and gemstone is unique, the precise choice has to be made.
They also advise that, if no person confident enough to advise us can be found, we should wear the crystal or gemstone for 3 days; if we don't notice any beneficial effects it should be put away and we should start seeking for the new one.
It is only the correctly chosen crystal or gemstone that reflects all of it's harmonious strength and wholeness by which it works, and the individual effects occur when the crystal or gemstone is being brought into contact with the skin of the person for whom it has been chosen.
Possible effects range from strong to subtle ones, and every effect affects the psychological as well as physical plane; knowledge of which is familiar to the expert person and could be passed on to you, too.