That's right," said Door. Her cheek lightly grazed and her dirty reddish hair was tangled; tangled but not matted. And her eyes...Richard realized that he could not tell what color her eyes were. They were not blue, or green, or brown, or gray; they reminded him of fire opals: there were burning greens and blues, and even reds and yellows that vanished and glinted as she moved.
Neil Gaiman, Neverwhere
eyes, opal