Scientists generally agree that humans began to see blue as a color when they started making blue pigments. Cave paintings from 20,000 years ago lack any blue color, since as previously mentioned, blue is rarely present in nature. About 6,000 years ago, humans began to develop blue colorants. Lapis, a semiprecious stone mined in Afghanistan, became highly prized among the Egyptians. They adored the bright blue color of this mineral. They used chemistry to combine the rare lapis with other ingredients, such as calcium and limestone, and generate other saturated blue pigments. It was at this time that an Egyptian word for "blue" emerged.

Slowly, the Egyptians spread their blue dyes throughout the word, passing them on to the Persians, Mesoamericans and Romans. The dyes were expensive -- only royalty could afford them. Thus, blue remained rare for many centuries, though it slowly became popular enough to earn its own name in various languages.