This trait causes the goo to have a gradient in either a single area or in multiple areas. Although it doesn't seem to affect a mhoat's eye color. If you'd like to have a gradient in their eyes they'd have the Fade Eyes trait instead.
These gradients appear in Single Tone Goo, Double Tones and can even appear with Triad Goo! As long as the associated traits are applied correctly.
Any gradients that are present on the mhoat's body are counted by the color that begins the gradient and the one that ends the gradient. If you decide to blend two completely different colors, any middle tone that would naturally occur between them, would not cause it to shift into triad.