Blue is a cool, soothing color within the auric spectrum. It corresponds to the element of water and to the Throat Chakra.
Keywords to describe a blue aura person would be: wise, loving, healing, calm, intellectual, compassionate, emotional, considerate, and self-aware.
A more in-depth analysis of what a blue aura means can be found in my previous entry here. Many shades of blue are listed, so you can find your specific shade meaning easily. :)