No you don't want to breed those two colors together and Lav is still somewhat in the project stage.
Why not? They use black.
Because both the blue and the lavender genes dilute black pigment. The blue gene dilutes all black pigment in a black bird to a grey color (the shade can vary). The lavender gene dilutes all black pigment in a black bird to the lavender color (which is a uniform shade of grey). Also, lavender is a simple recessive, if you have two copies of the lavender gene you have a lavender bird. If you only have one, you have a black bird. Blue is not a simple recessive, if you have two copies of blue you have a splash bird, if you only have one copy you have a blue bird. If you cross blue and lavender birds, you will end up with a muddy genetic mess that will take years to work out. Using black works because it is the "base" color so to speak and you don't have to worry about colors leaking.
Ah. Thank you