Selfs are unicolored birds with no marking. But that doesn't mean that aren't pretty.
Except the whites, they all became very rare. You can find them in three varieties: with smooth wingshields, with bars and checked.
The shortage of good breeding-animals resulted that the selfs became unpopular. Only the whites are popular.
Because the selfs don't have markings, people think they are to breed (at least when there are enough breeding-animals available). This is not always true. The standard level of the self whites is high.
The crossbreeding of selfs of different colors (for example: blue x white or blue vs ash-yellow) is very interestingly. It also includes surprising results.