- God;
- the gods;
- Amethyst, Princess of Gemworld.
Dr. Fate? His swag comes from Gemworld.
Dream of the Endless? Connected to the gems of Gemworld.
The Lords of Order and Chaos? Yep, Gemworld.
Mordru? Comes from Gemworld.
Arion? Emprisoned on Gemworld.
Zerox the Sorcerors' Planet? Used to be Gemworld.

Amethyst, Princess of Gemworld is one of the most important comics in the entire DC Universe, yet it wasn't until last night that I finally read it for the first time.
Amethyst, Princess of Gemworld, wasn't supposed to be a pillar of the DCU. It was an experiment, designed specifically to attract young girls to reading comics (perhaps the first DC comic book to have that as a clear goal since Wonder Woman debuted over 40 years before). DC hoped to attract girl readers with a character rooted firmly in the fairytale princess genre.
Amethyst (a.k.a. Amy Winston) first appeared in an insert story in a Legion of Superheroes comic book (LSH 296, FEB 1983), a teaser for a 1983 "maxi-series"with a pre-set 12 issue run. I was in college at the time; Amethyst just didn't make it onto my reading list, as I'm sure you'll understand.

Amethyst could have been just a silly "Rainbow Brite"-style ponies-and-princesses story, and frankly that's what I was expecting when I read it. To be sure, it has many trite tropes of the genre: Amy Winston learns on her 13th birthday that she was adopted and that she's actually a princess of an other dimensional world of magic, whisked away to earth as an infant when her planet with overtaken by a evil despot (Dark Opal).
But somehow, either through the genius of the writers (Dan Mishkin & Gary Cohn as enhanced by the art of Ernie Colon at the top of his game) or the crosspollination with other comic book genres (such as superheroes, sword & sorceror, and even some heroic animal comics), Amethyst transcended expectations.
Don't believe me? On page two, Amy's a happy little suburban girl, anxious to open her birthday gifts. By page six, she's about to be raped by two large trolls. You heard me. Amy is physically older when she's in Gemworld, which in the hands of lesser writers would have culminated with "now I can wear grown-up dresses and jewelry, whee!" But this is not fairyland, it's Gemworld; Amy has to deal (repeatedly) with the ugly fact that being the adult Amethyst has its unpleasant side. A kidnapper (albeit one more handsome than a troll) starts to rape her in issue 2; he does not succeed. It's now one of my favorite "calvary to rescue" scenes in all of comics, because it teaches an important lesson: do NOT **** with dogs.
Gemworld itself had a rich backstory and a host of interesting characters and, impressively, the "real word" supporting cast was well fleshed out, too. Amy's adoptive mother was a child psychologist who would naturally use her "techniques" on Amy -- and Amy, no fool, would call her on it. Amy's father, an English professor at Hudson University (anyone remember Hudson U?), was a model parent in dealing with Amy's complicated situation, without coming across as a ridiculously "perfect person". And Amy's dog, Taffy? Taffy is one of the DCU's Top Five Dogs of all time (with Krypto, Ace, Rex, and Pooch).
A few years after her maxiseries, Amethyst got a regular series, but the Crisis was fast approaching and Amethyst did not survive it. But both pre- and post-Crisis, something odd happened; writers and editors kept linking bits of DC's magic-verse to Gemworld. A lark? A fanboy nod? A simple snowball effect? Regardless why it happened, a lot of the magic left in the DCU (well, at least before the Spectre got snitty about it) is linked somehow to Gemworld. In a sense, you can't really understand the big picture of the DCU without knowing Gemworld.
Yet (to my knowledge), Amethyst's series have never been reprinted.
DC: why have you not gathered Amethyst's two series in trade, archive, or showcase format?