The original meaning of cyan is blue, the color of blue ore or vegetation, and later it is extended to green and black. In Shuo Wen Jie Zi, green is also the color of the East. So green can refer to the east and spring, and its meaning can be extended to turquoise grass, immature crops and bamboo slips, which are full of vitality.

In ancient China, colors were divided into positive colors and intermediate colors: "positive colors" cyan, red, yellow, white and black. "Intermittent colors" green, red, blue, purple, yellow, yellow land, red flame, blood, blue sky and green water alternate day and night, which constitutes the basic color summary of primitive people to the whole nature.

Cyan is a color between green and blue, with a wavelength of about 500-485 nm. There is no uniform definition of cyan, which varies from person to person. Generally, it can refer to various colors between blue and green, while dark cyan is a deeper cyan.

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For example, there is a kind of blue, such as Tsing Yi and cyan robes, which are relatively light blue. "A green flower grows in my heart", which is one kind of blue, and the other kind of blue is black, such as indigo or moss (women's hair).

When we understand cyan, we should not simply regard cyan as green, but be flexible. The blue sky we usually say is the blue sky. Sky blue (slightly lighter blue), also known as cyan, the cyan of Bao Qingtian may refer to dark skin color on the one hand, and Ming Che is more like a blue sky on the other.