Natural is valued way less. The only way natural pets can be significantly valuable is if they're on a seasonal/CS or have an extremely good name.Other colors are rare because they all have different hatch rarities. Such as albino; it's more difficult to hatch one compared to all the other colors.
The only valued and sought-after colors are Gingers, Silvers, Blondes, Calico, and Albinos. Because Kir mostly ask for those types of colors.
But yeah, different colors on certain types of creatu species are valued differently, unless the creatu themselves have the same rarity and color.