Can't Remember the title of a book a read

[teemun]

Hey everyone,

So I read this book (or most of it) when I was a kid around ten years ago, and I really want to read it again. But for the life of me I can not remember the Title or the author.

I remember it being about a boy who lived in a giant castle/ tower structure. Their society was separated by a hierarchy of colors. He was an orange and one of the lowest I believe, but one day he made it up to the Violet level by sneaking up there. Everyone wore crystals around their necks and could do some sort of magic with them. The last part I remember of the book he was kicked out of his home and woke up on some sort of ship in the winter.

I know this is pretty vague but any help would be greatly appreciated.

Thanks so much in advance!

[fjm2]

This sounds like Garth Nix's Seventh Tower series, although I thought it was rather more recent than 10 years ago.