Creating niche colors by mixing blue involves combining it with other colors in varying proportions. Niche colors are those that are less common and often have a unique, subtle, or artistic quality. By adjusting the amounts of additional colors like red, yellow, green, or purple, one can create a wide range of hues that may not be found in standard color palettes. These colors are often used in design, art, and fashion to express individuality or a specific mood or theme.