When hatcheries ship chicks as "Blue" it is actually usually three different colored chicks combined .. Blue, Black and Splash ... they are genetically three different colors, Blue is not a true breeding color and you wind up with all three colors when you use Blue parents (Bl/bl+ is blue, Bl/Bl is splash, bl+/bl+ is black) Feathersite has pictures of the different colors as chicks if that helps.
chicks http://feathersite.com/Poultry/CGA/Cochins/BRKCochChix.html
adults http://feathersite.com/Poultry/CGA/Cochins/BRKCochinBty.html
chicks http://feathersite.com/Poultry/CGA/Cochins/BRKCochChix.html
adults http://feathersite.com/Poultry/CGA/Cochins/BRKCochinBty.html