We spotted these beautiful, plant-based food colorings at Natural Products Expo West; they're completely free of creepy artificials like Red #40 or Yellow #5. When asked whether they work for Easter eggs, they helpfully replied: "We have had success with Blue, Yellow, and Orange. We found the red coloring turns the eggshell to a dark maroon/ deep purple (not as attractive as we would like). We used 1 packet color to 1 cup of water, plus 1 teaspoon baking soda or vinegar."