If you are choosing a wand for yourself or to use on someone else, the same principle applies. A simple test to see if a crystal is right for you or not is to hold it in your hand. If your breathing slows down and you feel relaxed, then this is a great crystal for you. If your breath shortens, then try another crystal until you find one that feels calming.
Another test is the pendulum method. Hold the crystal wand in your hand while standing up with both feet flat on the ground. With your eyes closed, ask the question to yourself “Is this the right crystal for me”. If you find yourself tilting forward, that means ‘yes’. If you find yourself tilting backwards, that is a no. And no movement is usually neutral.