Uno: I wouldn't buy anything based on that photo.
Duo: I think I see the outline of wattles, which would indicate male.
Tres: Crest is rather messy, which could also indicate male.
Quattor: Ask for another picture. Because that silkie looks silver partridge, and silver partridge is cool. EDT: and therefore, missing out on buying one due to a mis-sexing based on a bad photo would be a tragedy.