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. read more
Using the food coloring illustrated below, I first added a lot of blue until it was as dark as I could make it. Then I added a little black and a little purple. I kept adding blue, black and purple gradually until it looked right. I was just winging it, but this website— How to Make Navy Blue Royal Icing —suggests the following ratios. read more