Blue, Green, Grey & all shades of Brown Eyes
The darker ring around the iris is the ring of purpose (look for the thicker dark edge near the white of the eye /sclera).
The first two pictures show a Ring of Purpose but the third does not have one.
Check this youtube video of famous people's eyes Click Here
The Meaning of Ring of Purpose
Darker outer ring of the iris
This person will know what he/she is doing in life, Capable of anything, may seem arrogant or confidant.
Greatest strength- poise, calmness
People with the Ring of Purpose...
need to go after their Purpose in Life. They DREAM BIG! If a person with this marking does not know their purpose they will feel empty. They have to be on their path, going for their dreams and turning them into reality.