It is not a veneer. It looks like a very thin film layer. On YouTube there is a video by a guy who repaired the cracked photo flame layer on the headstock of a BBG. He removed the aged and cracked film, and replaced it with real veneer. Very clever.
There was also one on eBay, in Italy I think, with very obvious age cracking of the film on the lower bout of the body.
It is correct that the film does not show the chatoyance of a real veneer, which is a dead giveaway. I think they are beautiful and very playable basses, photo or no.