It is my understanding that original studies go back to quail, however the lavender gene is a mutation. The article discusses the gene in some length. I'll see if I can find the one that discusses the quail crosses that were performed to test this mutation.
http://jcs.biologists.org/cgi/reprint/51/1/25.pdf
http://jcs.biologists.org/cgi/reprint/51/1/25.pdf