The iris gives eyes their color and the color depends on how much melanin (pigment) the iris contains. Eye color is also determined by the front layer or stroma of the iris. It contains the melanocyte cells that produce melanin as well as fibers that scatter the light that is reflected outward. As many as 50 genes may have influence on eye color and the genetics of eye color is quite complicated. Eye color can range from the darkest shades of brown to the lightest tints of blue or gray. There can also be a gradation of color from the pupil out to the edge of the iris.
Eye color does not change, and in most people eye color is fixed after the first year of life. If there appears to be a change in eye color, an ophthalmologist should be consulted. Wearing certain colors may make eyes seem to take on a different color hue, but the wavelength reflected will be the same. There is controversy over whether emotions, particularly anger, can cause eye color to change. Red dilated blood vessels in the eyes may make the iris appear darker and the dilation of pupils during grief may make the eye color seem darker because the pupil is so black.