How to use the Illustrator gradient color tool is Adobe Illustrator is fairly simple. This tool provides you with the option of adding a gradient fill in illustrator to your art work. Through this you can add a blend of colors to your drawing. It is also very simple to change the gradient fill of any object you seem to be working on. Illustrator gradient color can also be used to give a 3-D effect to your image with just varying colors inside it.