Hand your friend a crystal and measure the energy field. Write down your results. Hold the crystal to your forehead and recall a time you felt angry. Hand the crystal back to your friend, and measure the energy field again. Have your friend say the Light Invocation three times out loud, and once more, measure the energy field.
Negative emotions cause a reduction in human energy fields.
If the negative emotion charged crystal causes a reduction in the measurable field, you know the crystal is holding or storing negative emotions. If the energy measurement increases after the Light Invocation beyond the original measurement, two things are possible. First, the Light Invocation does, indeed, clear out negative emotions. Second, the Light Invocation also increases the overall energy field. Cleansing is a process of reducing the negative emotional energy level of the crystal to the point where the emotional energy can no longer affect you.