If both parents are purebred and have a full (breeding) registration by the AKC then they are registered. Mego is correct. The color has nothing to do with it. You don't know what you will get though because white masks the true color of the dog.
Some AKC dogs have a "limited registration" and their offspring cannot be registered. A full registration certificate has a purple border and limited has orange.
That said, having an AKC certificate only means the dog is purebred, assuming the breeders were honest that the parents listed on the registration are, in fact, the correct parents. It is no guarantee of quality.