I am midway through the reading of Barry Lopez's Arctic Dreams, a meditation on the Arctic and our place in it and in the world, and came across this stunning description of the color of polar bears:
The ivory and pearl shading we see in a polar bear’s fur is caused by the refraction of sunlight (the same phenomenon that makes clouds appear white) in its guard hairs. The hair itself is optically transparent, or colorless. The brightest whites show up at the spring molt, the purest of these being those of young cubs. With exposure to sunlight, the hairs take on a subtle coloring; soft yellowish tones appear on the hips, along the flanks, and down the legs—a pale lemon wash, apricot yellows, cream buffs, straw whites. The tones deepen each year as the animal ages. In the low sunlight of a fall afternoon an older male’s fur might suggest the yellow golds of ripe wheat.Above is my poor attempt to reproduce the polar bear palette in Photoshop.