Elim Garak has one of the more hard to describe skintones of any Cardassian on DS9. It’s highly subject to look much different depending on the lighting of the room he is in. 

His father, Enabran Tain, hails from the northern provinces of Cardassia as indicated by his grayer skintone and more ovoid eye ridges that let in more light from the periphery of his vision. Damar hails from this region as well.

His mother, Mila Garak hails from the poorer central provinces along the equator and has the more beige-y skintone to blend in with the sand and the more circular eye ridges to shade from the harsh desert light. Dukat also comes from this region.

These two phenotypes mix to produce a rather seafoam-y skintone seen on Garak. Tain’s blue undertones and Mila’s underlying yellow combine to form a more pure grey-green. Garak was lucky enough to inherit his mother’s eye ridge shape rather than his father’s.

Cardassian blood is a much darker red and thicker than that of humans (see ‘Our Man Bashir’ and 'Way of the Warrior’) but their flesh is lighter in color - almost white in some places. the darker red combined with the lighter flesh makes for a pinkish flush around the lips and eyes where the skin is thinnest. 

The blue seen in his chufa ridge during a few of the episodes is an opaque creme makeup that is more commonly used by females. Garak doesn’t have much of it, and therefore only uses the smallest amount for a subtle blue flush which he thinks is classier than just filling in the whole area with pigment. In a sense, he’s being cheeky about it - using just enough to make a visible difference, yet blending it out so one questions whether it’s there at all.