1. A color adjustment apparatus comprising: a pair generating section that generates plural pairs of a plurality of colors in a first color gamut and a plurality of colors in a second color gamut, which correspond to the colors in the first color gamut, respectively, wherein one of the pairs includes white in the first color gamut; a vector generating section that generates a plurality of vectors connecting each color in the first color gamut and each color in the second color gamut, which belong to a generated pair; a weight calculating section that calculates weights in accordance with distances between each color, which is to be processed and is in the first color gamut, and origins of the generated vectors; a synthesized-vector generating section that applies each calculated weight to the corresponding vector to generate a synthesized vector; and a color converting section that converts a color, in the first color gamut, to be processed into a color in the second color gamut, using the synthesized vector.