I was on this site once, that was based on a book series I don't even remember the name of.
all I remember is that gems were power for angels?
This is probably wrong, but are you thinking Black Jewels by Anne Bishop? They had jewels/gems that basically indicated the strength of their power or something. I know there were lords... and ... ... ...that's it. 8| Does that sound familiar?
Oh, but there's another one I remember that had to do with gems... I think it was inspired by an old video game.It's been so long, I don't remember the site or the game it was based off. Pretty sure it was Legend of Mana but not 100% sure. I tried to find the site via google, but I don't remember the host or the name of the forum. orz
Edit: I think you might be thinking of Black Jewels... I've never read the books, so either BJ or someone's original twist on BJ