Yes I've seen them on some onyx picassos. Check this pair out from clownfish depot. The female is a Cquest and you can see the very slight pinch on the head. The male I believe is a doni picasso x onyx cross. You can see the blue hues.
http://community.lovenature.com/wp-content/uploads/sites/4/2016/03/Clownfish_2.jpg
Here's Rod's onyx mama clownfish with the classic pinched head.
https://reefbuilders.com/files/2012/01/greenonyx01.jpg
Wow crazy! Thanks.