I'm afraid it doesn't have the word Jade in it (don't know how much of a deal breaker it is) but my all time favourite horror novel and one I strongly recommend is Stephen Kings IT - and its 1,200 pages long!
If you've never tried Stephen King and you think he might not be for you I would still suggest trying IT - yes it's a horror novel but it's also a novel about the unbreakable friendships you have as youngsters - or so you believe - that time slowly breaks, it's about the highs and lows of being a child/ young teenager, and the endless days of summer. For me it perfectly captures the feelings of childhood/ adolescents. It is the one book of mine that I have read more than any other, and it's the book that got me into reading so holds a special place in my heart
** Be warned there are a couple of scenes in the book some people (including myself) may find disagreeable/ hard to digest - but they don't ruin the book**