Royal Blue Icing Color Wilton This gel-based Royal Blue icing color gives you deep, rich color that won't change the consistency of your sweet treat. Perfect for coloring buttercream frosting, fondant, royal icing and more, this blue gel food coloring is highly concentrated, so a little goes a long way. Get a cool, dark blue buttercream for a winter cake or a saturated, deep blue for a striking birthday or wedding treat. Simply apply a small amount of food dye to your frosting or fondant using a toothpick, then mix to incorporate. Add more to deepen and darken the color. Also safe to use in batters, doughs and other foods, this edible blue food dye is a great way to customize and personalize your treats.