Gradation of color is a term used to describe the gradual transition between different shades of a single color. It is often used in art and design to create a sense of depth and movement. The term 'HUE' is used to refer to the basic color of an object, such as red, blue, or yellow. HUE is one of the three properties of color, along with saturation and value. Gradation of color is achieved by gradually changing the HUE of a color, creating a smooth transition from one shade to another.