A polished tile with dark color looks ugly if the manufacturer uses only regular gloss material. As you know dark colors absorb most of the rays of light. So to make a dark surface shinier, they need to use extra gloss (hi-gloss). Please see the diagram on left >>> Apparently the light colors don't need extra gloss. So BE CAREFUL if someone trying to sell you a light color at a higher price saying it is Hi-Gloss. The normal glaze is good enough for all light colors. Dark color has a higher price because more amount (gram) of glaze is used.