Blue merles and blacks have black pigmentation on the nose (and lips). Red merles and reds have liver (brown) pigmentation on the nose (and lips).

For the AKC: On the merles it is permissible to have small pink spots; however, they should not exceed 25% of the nose on dogs over one year of age, which is a serious fault.

It is generally assumed that dogs may have pink on their nose up to a year in ASCA.

Here is a blurry image of a butterfly nose. (with lots of pink). A dudley nose is a nose with no pigmentation at all. This is also a liver-colored nose.

Black nose.