The Color attribute of particles affects their display in the viewports. It does not necessarily affect their rendered color. Some shaders make use of the ICE Color attribute automatically, but in other cases you may need to use an attribute shader to get the Color attribute and plug it into the appropriate shader port (see [ ]). The Color attribute does not affect the viewport color of points on polygon meshes or other types of geometry.
The Color category contains a couple of nodes designed to perform basic math operations with colors: Add Color. Subtract Color, and Multiply Color by Scalar. They operate on each channel independently. Unlike the ordinary math nodes, these nodes provide options for:
You can read from and write to vertex colors (also known as color at vertices properties, or CAVs) in ICE trees. To do so, you connect to the Colors attribute of the vertex color property found under the appropriate cluster.