Kittens are born with their eyes closed, and when they first open them, usually around 1 to 2 weeks of age, their eye color appears blue due to immature pigmentation. The process of their eye color changing from the initial blue to their permanent color typically begins around 6 to 7 weeks old. This color change is gradual and usually completes by the time the kittens are about 12 to 16 weeks old. By around 7 weeks, the adult eye color starts to emerge. The final eye color can range widely, including shades of green, yellow, amber, or brown, depending largely on genetics and breed. Some breeds, like Siamese cats, may retain their blue eyes into adulthood. In summary, kittens' eyes generally change color from blue to their permanent color mostly between 6 and 16 weeks of age, with many settling around 7 to 8 weeks.