I guess, you imported the skin from maya. So you should look at the skin settings in MED:
Edit Menue >> Manage Skins
Klick here on the Skin ("Skin 0" for example), then it should display the format as well as the color depth.
You can also adjust the color depth if you klick on the Skin Settings Button and then on "Texture Format" (all Buttons in the Skin Manager panel).
Make sure, that you import a texture format that is supported by GS, such as .pcx, .bmp or .tga for best quality. DDS is also possible, but doesn´t show up in MED.