Pink: Pink means exactly that, pink. This applies to the very fair skinned up to those of deeper tones who burn easily, bringing out the reddish pink hue pigment in their skin. Such colors in this category have the words "ivory","fair", and "beige" in their color name. One tell tale sign is that the veins on your body will show through in a blue toned hue.
Yellow: This undertone is for those who do not burn easily and whose skin turns golden in the sun. A person in this color range will have greenish hued veins. Words such as "golden", "sand", "tan", and "beige" are found in this color selection. Many people in the yellow category can also fall in the "neutral" family of foundations, which means that they have some redness in the face.
Cool: Neutral or pink based undertones fit in the "cool" category. Very fair to women of color with a reddish undertone are in this group.