The eye color is genetically determined. Pigment-cells in the iris contain brown, black or yellow particles. Blue and green eyes are caused by reflection of light by different colored pigment.
Because of the lack of pigment in blue eyes, there is more sunlight absorbed that is used to make vitamin D. That’s why cats with blue eyes are usually found in areas where there isn’t much sunlight.
This color looks the most like the eye color of wild cats. A lot of green eyes are brown or yellow first before they get their final color. Copper colored eyes often become ‘blur’ when the cat gets older.
Green eyes are common with breedless cats. Some breeds distinguish themselves with different shades of green. The sea colored eyes of the Chinchilla are probably an intermediate color to blue.
Kittens are born with blue eyes. The color will change when they grow older. Full grown cats can have eyes in the colors green, orange, yellow, green, copper and blue.
Cats/Focus by Dr. Bruce Fogle