Normal perceivers divide into different groups on whether a body's color is unique blue, slightly reddish-blue, more reddish blue, or greenish blue.

Another major problem for the realist version of Color Primitivism is one that Hardin (2004, 2008) and Cohen (2009) have especially stressed. They draw attention to a vast range of facts concerning the variety of conditions under which objects appear to have the colors they do, and the variety of classes of observers for whom the colors appear. Since the only way to determine what primitivist color a body has is by the way it appears, this raises the question of which is the body’s real color. N