It depends on a combination of genes. For every feature is responsible a group of genes, not just one gene. So it is also for eye color.
Suppose that parents with a black, very dark eyes, should not expect a blue-eyed child. People with brown hair and eyes, can have a child with blue eyes, but more common are cases their children to have eyes as well as parents, ie brown. People with light eyes and hair, have the greatest chance that their child will have blue or green eyes.
If one parent has light brown eyes, and the other blue, then the eyes of a child may have any of the colors. Researchers say that big lips are usually inherited from the father, and that, in general, girls always look more like their father, and the boys like mother.
The boys receive from the mother one X chromosome, which determines their appearance, and the girls get one X chromosome from both parents. Hair color also follows similar rules present in determining eye color.
The darker or lighter shades depending on the amount of melanin.