That's pretty much my understanding also. Certain breeds usually call it lavender, and other breeds call it self-blue, but basically the same. I had a self-blue Slate turkey. I'm planning to get self-blue OEGB's, but I have lavender orpingtons! LOL I have blue cochins, but I think just blue, not self-blue.
There is a genetic difference between the blue that comes from blue/black/splash genes and lavender genes, but I can't explain it enough to make sense. Lavenders and self-blues carry 2 copies of the lavender gene. I know nothing on the Isabell side.
Lol everytime I see your Lav Orps hatch I keep telling myself I need to get some of those!
Yes, you're exactly right- the Blue gene color is totally different than self-blue. The easiest way I can explain it, is that Blue doesn't breed true. It dilutes black to different degrees. For example:
Blue x Blue = 50% blue, 25% black, 25% splash offspring
Blue x Black= 50% blue, 50% black
Blue x splash= 50% blue, 50% splash
Black x splash= 100% blue
Self-blue(Lav) x Self-blue(Lav) = 100% Self-blue (Lav) offspring
If you cross a self blue with a solid bird of a different color- say, a solid black, you get:
Self blue(Lav) x Black= 100% black "split" offspring (split for lavender). Birds carry the lavender gene but appear solid black.
Along with the self blues, I really like the Blue color too. I have BBS Copper Marans, large fowl blue and black Cochins, and my month old bantam BBS mottled Cochins. 😄
Ive been thinking about starting a self-blue mottled bantam cochin project down the road. I haven't seen that combination yet but I bet it would be really pretty!