A general guideline. Source: http://www.newkidscenter.com/Baby-Eye- Color.html
A child’s eye color depends on the genetic material of each parent. Genes come in pairs. One is usually dominate and overrides the other gene which is recessive. A recessive gene only has an effect if both genes in a pair are recessive. In simple term (although it is really not that simple), brown is the dominant gene, blue is a recessive gene. Depending on the genetic make up of the parents, these genes can mix and match in different ways to create different eye colors.
Babies are usually born with lighter color eyes. As they grow, they produce more melanin (pigment), which changes their eye color. The amount of melanin one has is also based on genetics. Therefore, an individual with blue eyes can have very light blue color, a dark blue color or any shade of blue in between. Albino eyes have no pigment at all and so their eyes appear pink or red because of the reflection of blood vessels in the back of the eye. Green eyes are the rarest, only 2% of the world’s population have green eyes and they are mostly in Iceland.
Eye colors can change a little bit with age, however should not change dramatically. If your child has 2 different color eyes, or if you notice your eye color has changed dramatically, you need to inform your optometrist as this may be indicative of eye disease such as Horner’s Syndrome.