Blue can be harmonized with the secondary colors green and purple. It can also match the tertiary colors of blue-green, often called cyan, and blue-purple, often called ultramarine, based on analogous colors. Blue harmonizes with orange based on complementary colors, according to basic color theory.
Other colors that match blue may be based on natural color schemes. Blue, being a basic color in the water and the sky of Earth, often pairs well with greens and browns.
Throughout human history, there have been a number of natural materials used to create blue dyes. Cobalt-based blue pigments, lapis lazuli mineral deposits and indigo plant dyes have all been used.
