Have you noticed that the color blue is scarce in nature?
The most brilliantly blue things, like a peacock feather or even a human blue eye, don’t have a single bit of blue pigment in them. “Blue is fascinating because the vast majority of animals are incapable of making it with pigments,” says evolutionary biologist Rick Prum. Instead, many have developed structures on their surface that bounces light in just the right way to make them appear bright blue to the viewer.
Same applies to icebergs.