There is more than one color in the aura. If you can see auras, keep in mind that you are seeing them through your own aura. Often, the subconscious is aware of this and makes adjustments, however. Do not make judgments on people based on what you see in their auras. Use your intuition when interpreting how the aura looks.
Auras change frequently.
The colors about a foot or two from the body go through many changes in a single day. You will find, however that a person has a predominant color that stays with him through life. This is an exercise for cleansing and purifying the entire auric field. It is great to perform at the end of a day when you have interacted with many people. It helps sweep out energy debris .