The basic color combination that makes purple or violet is blue and red. Blue and red are primary colors. However, to get a violet or purple color that is not muddy looking, one needs the right types of blue and red colors.
When one is mixing red or blue paint, it is important to know that these paints contain other pigments. For this reason, one needs to find the correct blue and red to avoid this muddiness in the violet color. For example, one should choose a red paint that does not contain yellow pigment and is closer to the color dark pink. Similarly, one should use a blue paint that does not have any yellow, red or green pigments in it. To make a pure violet color, one can also use a combination of paint colors that are marked as warm red and cool blue.