Well, it’s blue, at least according to an internet pole on about.com
Color Psychology 101: What Is Color?
In 1666, English scientist Sir Isaac Newton discovered that when pure white light is passed through a prism, it separates into all of the visible colors. Newton also found that each color is comprised of a single wavelength and cannot be separated any further into other colors. Read more about colors and color psychology on About.com
Also see: The Synesthetic Alphabet