Once again - height can help you determine the authenticity of this cookie jar. McCoy Mammy Cookie Jar Front Original Mammy is a full 11 inches tall and does come in white, yellow, and aqua. The bottom is marked McCoy and has a glazed bottom with a dry ring foot. Details on this example are cold painted, on top of the glaze and show much wear. Unfortunately it is marked the same and the cold painted details can be scratched to look as if it has aged.
Height is the best indicator to help authenticate the jar as genuine.
You do not need to measure the height to be sure you are looking at a reproduction. If its marked McCoy, it is not the original cookie jar. There are other reproductions of this jar in the marketplace. Other color combinations have been found in the reproductions.