As per Chuck B.
Type 1: A clear base glass with a color patch on top, a white patch on the bottom
and a two color (half and half) ribbon in the middle. (More Common Tri-colored Tiger-eye)
Type 2: A clear base glass with a color patch on top, a different color patch on the bottom and a one color (half and half) ribbon in the middle.
(Not very common - a fancy version of Type 1. Rarer still if it has a two color (half & half) ribbon."
Type 3: A clear base glass with a color patch on top, a different color patch on the bottom and a white (half and half) ribbon in the middle.
Type 4: An opaque white base with a color patch on top, a different color patch on the bottom and a white (half and half) ribbon in the middle.