A crystal grid is arranging crystals in a way to increase the “energy” or “vibration” of your intention. An intention can be whatever it is that you want to honor or manifest in life. Perhaps you want to create something to send healing to a sick loved one or attract wealth into your life. A crystal grid is a fun way to express yourself and use your crystals in a creative way.
I personally feel that what crystals to use and how to arrange them, is based on a person’s individuality and intuition. It’s okay to have a totally different perspective on how you want to arrange them and what you’re drawn to. It can be an interesting way to develop your own intuition and explore your personal creativity. Have fun with your own process and let it take you where your heart wants to go.
As far as choosing a crystal, go with your intuition. Try and clear your mind and go with whatever you feel drawn to. It can be for the color, texture, size. The reason doesn’t necessarily matter because often times the crystal “chooses” you. There is no wrong choice and no crystal that is “bad” to go with.