You cannot change the color of your nipples
Nipples become darker when pregnant
A female dog's nipples will change color when it is pregnant. They usually change to a brighter red color, and usually grow.
Some nipples are differnt mainly because the color is varied in other parts of the skin. There is no problem with it.
You either have them or you don't. You can not change the color.
Her nipples are BLUE
Her skin tone.
The distribution of pigment makes the skin tougher.
darker hue then they normaly are