It's a custom model
. Not an original Jem, not sure why Stefan labels it as such - maybe because of the swirl and RG shape.
The body could be original Ibanez RG570/770.
The neck could be from a 7PBK, but it can also be a custom made neck.
Although, if neck or body was original I would think that was a selling point and worth mentioning. I know Stefan is a member of this forum, so maybe he can shed some light on the details. You can also e-mail and ask, he's a guy with good reputation (as far as I know).