I'm not sure
I've contacted the breeder, and he has informed me that the violet he is breeding originated from a male. I replied to him with several other questions, and awaiting answers, but if that is the case, and they originate from blue parents, it is not likely sex-lined. He also has a bronze bird he calls Creme-Bronze. though the photos are not very close-up, it looks as though the bird is bronze in colour, but with a light brown wing pattern. He has informed me that these birds originate in Italy. Check out his website http://www.exotic-farm.de for photos.