Crested guinea pigs conform to the Self colours, but have a crest or rosette on their forehead. Self Crested guinea pigs have a crest the same colour as their body colour, whereas American Crested have a crest that is a different colour to their body colour, commonly a white crest on a solid coloured body. The crested gene is dominant to non-crested, so that a smooth guinea pig bred from a crested parent cannot be a crested carrier.
Due to selective breeding most breeds also have a crested counterpart e.g. Agouti, Himalayan, Roan and Dalmatian. A Crested mated with a Sheltie is how the Coronet breed was created. The coronet is a relatively new breed, first recognised in the early 1970s.