It has been over a decade since Michael Muenks and I started re-creating bantam lavender Ameraucanas (in 2005). Michael used lavender Old English Game and I used lavender d'Anver to bring in the lavender gene/color. We both crossed to black Ameraucanas. (update...There were bantam lavender Ameraucanas bred and exhibited by a few members in the late 1980s and early 1990s, but they didn't catch on and those lines are believed to be extinct...2/9/2018)
I also started developing large fowl lavenders, in 2005, using the bantams crossed to large fowl black Ameraucanas. (corrected "2006" to "2005", on 1/30/17)
Lavender and blue are very similar, but different colors created by different genes. They look like shades of gray to me with lavender being lighter and more of an even color. Before the lavender gene was properly identified and labeled "lavender" (lav) the variety (color) it created was named "self blue". The word "self" means "same"; different breeders use it in different ways, but here it was meant that the blue color was the same all over the bird without lacing or any other variation. Today we know that both the phenotype and genotype of lavender and self blue are different. Blue is created when an otherwise black bird has one copy of the dominant blue (Bl) gene. It doesn't breed true. A blue chicken bred to a blue chicken will produce black, splash and blue chicks. I don't know of any breeds that have a true "self blue" variety recognized according to the dictionary definition. Andalusian blue would be a prime example of the blue (Bl) color, but it has lacing so it is not what they call "self" blue. Lavender on the other hand does breed true. A lavender chicken bred to a lavender chicken produces only lavender offspring (of course there are exceptions to every rule).
Since the APA and ABA officially call the lavender variety self blue they are the same variety according to them. Fred Jeffrey in his book BANTAM CHICKENS also lists at least 10 other names for this same color. So lavender and self blue are the same variety
or they are two different things, depending on the definition of the term "self blue" we are using at the time.
I've heard the term "self" used to describe that the crest on a Polish chicken was the same color as the rest of the bird, that a d'Uccle was not mottled and that a black bird without green sheen is self black. "Self" is an old term and is often very confusing. The standard uses variety names like buff, black and white without the word "self" as a prefix even though they are "self" colors, yet with blue they feel they need to include it. I guess when someone wants to get lavender silver or lavender wheaten recognized the powers that be will require name changes to "self blue silver" and "self blue wheaten". A lavender buff will have a difficult time getting recognized as "lavender buff" or "pink"! If bantam and/or large fowl Ameraucanas are ever recognized as such by the APA/ABA they should be recognized as "lavender" or not recognized at all. I've suggested to the APA that once lavender Ameraucanas are accepted they should refer to the APA's "self blue" PLUMAGE description (page 178 of my 1998 Standard) while retaining the official "lavender" variety name. Perhaps it would be a good time for the APA to include the lavender name as an alternative in the self blue description...such as "self blue/lavender". This isn't asking for any radical change or to have the Standards rewritten as some have claimed. Other breed clubs that want to get their lavender varieties accepted should be able to do the same or have them accepted under the self blue name if that is what they want. Some have suggested that all the current "self blue" varieties would have to agree to change them all to the lavender name or none at all. Again this isn't true. No one is asking them to change the names of their already accepted varieties or to correct the mistake in terminology, but welcome them to if they so desire. Radical change is not needed here and isn't being asked for. I would imagine that someday in the decades ahead all the misnamed self blues will be lavenders.
From the Dutch bantam book translated to english.
Lavender
In contrast to the blue, the colour lavender had no difference in shade between certain body parts. The aim is to achieve an even shade of silver gray all over the body and it is significantly lighter than blue.