Blue is a primary color, which means there is no color combination to produce it. Different shades of blue are possible to make through adding white to a blue base to create lighter shades or black to create darker shades.
Green, red and blue are the three primary colors of light. Mixing these colors creates new colors. For example, blue and red combine to make purple. Blue and yellow combine to create shades of green. Yellow and red create orange tones, and red and green merge to produce brown. Blue and green combine to make an aqua or blue-green color. Green and yellow mixes to create varying light-green shades.