Food coloring is a manmade pigment regulated by the U.S. Food and Drug Administration. According to the FDA, only nine certified colors are approved for use in food in the United States. Blending selections of the nine colors in different quantities and combinations will give the exact shade you need for your project. Dark colors are more difficult to achieve than light. Mixing navy blue, for instance, requires gel or paste food coloring to achieve the depth.
Mix one part royal blue paste or gel food coloring with one part violet paste or gel food coloring using a toothpick or chopstick.
Stir the colors together, thoroughly, using the toothpick or chopstick.
Add a tiny bit of black gel or paste food coloring until you reach the depth of color desired.
Colors will be different depending on the manufacturer and the medium.