Taken from Watershed3.tripod.com/types.html:
White or salmon pink faced Bettas in which the colours are splashed or blotched with no defined borders between the body and the fins or tail.
Two types of Marble Betta exist:
a) the traditional Marble or Piebald, which is a dark bodied fish with a white head or face and lacking in the colours red, green, blue and steel blue; and*
b) the Coloured Marble. The fins of the choice Coloured Marble show a sharp-edged mix of light and dark colours (red, green, blue, and steel blue) and the face and chin are white or pink / salmon coloured.*