You might want to use Google to find those names before hitting that 'send' button. Not trying to be mean here; just a friendly advice.
Certainly, usually it's difficult to guess a djinn's type of magic by its dungeon's appearance alone, but sometimes it does work (Zagan for example). And since we still haven't seen everything in Valefor's dungeon, there might be an indicator at some point.
Gyokuen? Let me try to remember the timeline a bit… Sinbad captured Valefor's dungeon when he was 15. Now he's 31, meaning all of that happened 16 years ago. Hakuryuu was 2 back then, with his mother- Gyokuen- still present. Therefore it's very, very unlikely for Gyokuen to have been part of Ja'far's clan.
I thought I was still on your ignore list.
I somehow forgot the plot with the first emperor marrying Gyokuen long ago. I am surely wrong about her being Gyokuen then. But they must be a reason why she is that great of a magician(I remember Gaming having to make quite some preparation before she could make that mirror ). Maybe Al-Tharmen investigating and manipulating the country like with Balbaad.
Their group of assassin is quite good anyway. I wonder what became of them.
For the google proposition I am on my phone most of the time and his internet connection sucks.
I'm a huge Magi fan with no one to talk to about the manga; at least not on the level I'd like. I take what I can get.