Abstract: A single layer roofing material having a headlap portion and a tab portion wherein the headlap portion has a color-value gradient or gradation and the tab portion has tabs and openings. The tabs may have a relatively uniform color. Openings between tabs expose the color gradient of the headlap portion when a first sheet of the roofing material is installed over a second sheet on a structure. A plurality of horizontal striations may be used to establish the desired color-value gradient. An illusion of depth or thickness is created when the roofing material is applied to a structure, such as a roof deck. The amount of tone and contrast may be selected to create the desired illusion of depth or thickness. The amount of contrast may be varied depending upon the color selected for each roofing material. The number of horizontal striations and their width may also be varied to provide the desired color-value gradient. Tab color, shape and size may also be varied to enhance the illusion of depth.