Skin Tone Studies

I'm creating a lecture and have been doing some skin tone demos for my Photoshop class. Here are some that were done so far illustrating the attributes of different skin tones. I thought it important to do studies of artists' work in order to see how they tackled skin tones rather than rely on photography. The artists I chose were J.W. Waterhouse, John Singer Sargent, Wong Kar-wai, Wai Ming and Gilbert Stuart. Feel free to use them if they are helpful. In order are: Mediterranean, African/Middle Eastern, Caucasian and Asian