ArcMap color ramps provide the means to apply a range of colors to a group of symbols. Color ramps are used, for example, in the Graduated colors layer symbology option. ArcMap algorithmic color ramps are a specific type of ramp that traverses the color spectrum between two end colors.
Follow these steps to create a new algorithmic color ramp in a style and edit its properties.
Open the Style Manager by clicking the Tools menu, click Styles, and click Style Manager.
From the left pane select the style where you want to create the new color ramp, for example, your personal style.
In the right pane double-click the Color Ramps folder.
In the right pane right-click in the pane, click New, then click Algorithmic Color Ramp.
On the Algorithmic Color Ramp properties dialog box, pick the start and end colors. Click Color 1 and use the dropdown arrow to select the start color. Click Color 2 and use the dropdown list to select the end color.
Click an algorithm.
Adjust the levels of black and white in the ramp using the sliders.
Click OK to close the dialog box.
In the Style Manager, give the new color ramp a name.