Kittens are born with blue eyes because their melanocytes haven’t started working yet. As they grow, their melanocytes start to function and the true color of their eyes begins to appear.
This is Chester the kitten. As he matures his eyes will darken to a copper color.
The adult eye color starts to appear between 4 and 6 weeks of age, and a kitten’s true eye color is usually apparent by the time he or she is 4 months old.