Combine ingredients for the base in a blender. Pour 2/3 of the base into a pitcher or large glass/bowl.
To the 1/3 base that is in the blender, add the blueberries to the base and blend just until the blueberries are smooth, and mixture is blue. Pour the blue layer into the bottom 1/3 of each glass.
Pour 1/3 of the white base into each glass to make middle ‘white’ layer.
Add the rest of the base back to blender and add strawberries (or raspberries). Blend until just smooth and divide evenly among each glass to make the red layer. Add a straw to each glass if desired, and enjoy right away, or place in the freezer for up to one hour before serving.