They say that beauty is in the eye of the beholder, but what do they say about the beauty of the eye, if, they in question, happen to be great scientific minds? In a basic sense, eye colour is determined by iris pigmentation, and how well the stroma of the iris is able to scatter light.
Human eyes can appear brown, blue, green or hazel, depending on how much melanin is concentrated in the iris, though this appearance is something of a natural magic trick:
