After green eyes, gray and silver eye color are among the rarer shades. The only eye colors more rare in humans are the honey-gold amber eye color and red eyes.
Sometimes gray eyes have blue in them and are classified as blue eyes because the lightest shades of blue eyes tend to look gray. Gray and light blue eyes have very little pigment in the iris. Gray eyes are more common in people of Eastern European origin than in other parts of the world.
Gray eyes are most commonly found in people in Northern and Eastern Europe. They can also be seen among people in North West Africa, the Middle East and Central Asia. However, the eye color among these groups is also rare.
Red eyes are the rarest. They appear in albinos, who lack pigment in their skin, hair and eyes. The red color is caused by blood leaking into the iris.