Mary
Mary knows all there is to know about color and color perception. She has a total and complete knowledge about it. She also has a complete knowledge of the physics of light and of the color spectrum.
But Mary has been brought up entirely in a black and white environment. She has never seen anything colored, only black, white, and shades of gray.
Mary doesn't have experience of seeing color. She doesn't know what is like to see color, despite all that knowledge.