The answer is simple. He has central heterochromia, a mix of pigments. The color of his eyes is not defined. Because there is not only one color : blue-gray, gray-green, light brown and a yellowish tone. His right eye has 4 as cores and left 3 colors. (Sorry if my english is not clear, I'm brazilian.) Any question? - por Duda Tanner
What is heterochromia:
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