Crystals and gemstones are living organisms. Crystals have a life energy of their own, they are alive and usually grow in clusters.
They are part of the Mineral Kingdom. All crystals 'vibrate' on their own individual frequency.
The frequency they send out will determine which crystal you will chose at a certain point in your life.
You do chose different crystals as your needs change. Many are as old as our planet and record the history of the planet.