When we describe someone's eyes as blue,technically we are referring to his or her blue:

Question

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When we describe someone's eyes as blue, we are technically referring to the color of their irises. The iris is the colored part of the eye that surrounds the pupil, which is the black center of the eye. The cornea is the clear outer covering of the eye, and the humours are the transparent fluids inside the eye that help it maintain its shape. Neither of these structures have color, so they cannot be the source of someone's blue eyes.

When We Describe Someone's Eyes as Blue,technically We Are Referring