A long time ago, in a galaxy far far away…

Between about 36,000 BBY and about 25,000 BBY, the Gems discovered the Star Wars Galaxy, and began forming colonies on various planets within it, Starting with the planet Tophsis, which, after a few thousand years, became like a second Homeworld, and was known to them and others as Christophsis. But many other planets also had Gem colonies upon them, such as Ilum, Ossus, Jedha, Mygeeto, Orax, Circarpous V, Nam Chorios, Corellia, Dantooine, Tatooine, Rafa V, Katak, Kesh, Phemis, Ruusan, Sigil, Indobok, Crait, Quarzite, Mastair, Jazbina, Lorrd, Simbarc, Lothal, Adega, Halm, Dolva Prime, and Krev Coeur.

Around this time, the Gems came into conflict with the Rakatan infinite empire, who, despite being very powerful in the force, particularly the dark side, and rather technologically advanced, they were unable to stop the gems advance. Eventually, they found the Je'daii order in the Tython System, and the gems established a colony on a planet there called Krev Coeur. The Rakata tried to convince the Je'daii that the Gems weren't good, and they didn't really seem to really care too much for organic force users, or any organic life, as they found it inferior and primitive to their own.

Naturally, this sparked a war between the two sides, one that the Je'daii seemed ill equipped for, due to the gem's superior technology, and seemingly endless connection to the force, even though they used it differently than organic beings did. But the Je'daii, despite being able to use the force for combat, mostly used metal swords at this time which were pretty ineffective against the gems' bodies and their gemstones. But, working together with Rakatan scientists, they managed to invent a new kind of weapon that could cut through almost anything, even the gem's bodies, using the gems shattered remains themselves to focus energy from a hilt into a blade made of plasma, the first lightsaber.

Even despite this new weapon, the war raged for a very long time, for perhaps a few hundred years, but then, the Je'daii realized they could use the pyramid ships that brought them to tython to effectively cut the gems in their galaxy off from the force by releasing a giant force wave that would permeate the galaxy, trapping the gems inside their gemstones, unable to form their solid hologram bodies. They did this, and the war basically ended, with the diamonds not wanting to come back after losing so much to these mere organics.

And of course, the gems went to earth about 6000 years before the events in SU, and their own war with each other began, with Rose quartz standing up to the diamonds. Even though she knew of the events that happened long ago between Gems and Je'daii, even though she never experienced them, she still believed that the organics of earth were good and worth saving, and that lead to the gem civil war, which Rose eventually won.

Thousands of years passed, with many signs that the gems had ever been there at all passing into myth and legend, but the Je'daii had experienced a schism within their order because of the war, with some arguing that the anger that they felt gave them greater power to destroy the gems, and those that disagreed. Leading to the splitting off of those who would become the Sith and Jedi we know today, and these two factions continued to war against each other for a long time, until of course, the Jedi were nearly wiped out during the clone wars by the scheming of Darth Sidious, and the betrayal of Anakin Skywalker, who became Darth Vader.

19 years after that happened, the death star was completed, and the events of a young half-human, half-Gem's life had been unfolding for a while, and during this time, a young moisture farmer on Tatooine whom I'm sure needs no introduction, and his best friend Biggs Darklighter, (who was in the imperial academy and was on leave back home on the Desert planet) were out looking for treasure in the Jundland Wastes, as they'd heard about a bunch of fancy gems just lying in a cave that were ripe for the taking, but no one else had really gone to because it was near a Krayt Dragon nest.

They found it, and tons of gems there, but Luke accidentally activated a wailing stone there (not sure how, as I think only gems can use them) which sent a signal out into the cosmos that eventually reached earth (and possibly Homeworld, though, I guess I haven't thought that they'd be involved so soon, but anything's possible.) and the gems picked it up, translated it, and thought that they should investigate (though I don't know how, as by this time they hadn't gotten the roaming eye, and weren't exactly willing to go to the other galaxy, since they knew what had happened there, and they didn't want to alert homeworld, which clearly would've been done the second they fixed the warp pad that would get them there, which would lead them to Tatooine, and the place where Biggs and Luke had just investigated about a week to a month prior, which happened to have a kindergarten near to it as well.)

The Gems, including Peridot and Lapis, plus of course Steven, Connie, and Lion (not sure about Lapis though, she might be unwilling to go to the other galaxy, knowing what's there. And maybe Connie might be kinda iffy too) they'd get there, and immediately be attacked by the Krayt dragons, forcing them to separate, with Lion warping steven and connie to another place on the planet.

They'd come across R2-D2, who'd just have gotten away from Luke and was trying to find Obi-wan, and then the young Skywalker himself, as well as C-3PO, and they'd probably encounter the Tusken Raiders as well, before being found by Obi-wan, and taken to his hut, while the crystal gems had been searching for them.

Also, I'm not sure if the gems would or should find Kenobi before or after they reunite with Steven and Connie. On one hand it might help establish them and what might happen between them early on, but this could present a problem, if they find out what he is, and the lightsaber he always carries might be a dead giveaway. Thankfully, he doesn't have any animosity towards them, and has become friendly with the gem shard in his own saber. But the Crystal gems still might not trust him for a while.

Alternatively, they might not meet him until after Steven and Connie have already met him, in which case, they might try to protect him from being hurt by them, because they probably wouldn't trust anyone like him, given their history, even though that was thousands of years ago.

And Luke might be kinda intrigued by all this, and the fact that there aren't just Jedi and Sith that use the force, that these other beings do too. He wouldn't know what to think of what Steven is, since he's organic and gem, but he'd probably really like him and be friendly with him, and Steven would do the same to him. Making it all the more tragic when Luke finds out that his family's been burned alive by the Empire, and Steven and Connie are there to see Owen and Beru's charred remains as well.

Luke wants to learn the ways of the Jedi, as his father did. And perhaps learn about the force from the Gems as well, so he can have a better understanding of how things are in the world.

After that, a bunch of stuff happens that's like what happened in the film (and you can change some of this if you want, I encourage it.) they go to Mos Eisley (with some of the Gems, like Lapis and Pearl not liking the way the place looks, but Amethyst actually enjoying it, and maybe she, Peridot and Garnet are the only ones who like Han Solo when they hire him. They also experience the cruelty and repression of the empire, and see that their own former masters weren't exactly the only ones to enforce tyranny among those less powerful than they are (just not sure how, maybe the stormtroopers would be shown abusing some aliens or trying to detain the Gems for some reason.)

Then they get to the death star, find out Alderaan's been destroyed, save Leia, whom Pearl might think is pretty cool, for a human, and Steven tries to prevent Obi-wan from dying, which ensues a fight between the gems and Vader, with the Sith lord pretty much taking every advantage, except maybe against Peridot, who magnetizes his suit, causing metal stuff to fly at him and delay him long enough for them to escape, but not before he poofs pearl. (also, the metal thing kinda might set up Vader's outrage at Peridot, which gets paid off when he shatters her in ESB. Though she might find out that gems were also used in the construction of the Death Star, as they're the same crystals that Jedi use in their lightsabers, which are gem shards.)

Anyway, death star goes boom, everyone's happy, and even Steven gets a medal! Yay! (and Vader also informs the Emperor of these mysterious beings who seemed to have a lot of force power within them, and Palpatine knows what they are too, since the dark Jedi and Sith that they eventually interbred with and became never really forgot the gems, and he knows what their return might mean for the galaxy. Which eventually might lead to the two sith lords going to Tython to find some documents about the war the Je'daii had with the gems, and how they might use the force against them as the ancients did.) But the problem remains of how they'll get back to earth. Peridot helps though, by inventing a new Hyperdrive that is much more powerful than any other they've seen yet in that galaxy, based on gem technology that allows them to travel much faster and farther than the older hyperdrives. And the first one she makes she installs on the Millennium Falcon itself, and gives the design schematics to the Rebel engineers so they can make more to help against the war with the empire.

They might even offer to give them safe haven on earth, perhaps at a cave to the north of Beach City, where they'd make a new base that the empire could never find, or if they could, couldn't reach without an advanced hyperdrive and/or Gem ship. They live there for a while, meeting people, helping the gems with their monster fighting, and still fighting evil in their own galaxy, and I think meeting Jasper and the rubies as well, who might go to the empire, and tell them where they are, and could help by joining with them, though, I doubt the diamonds would be too happy about that, so maybe they wouldn't. But either way, it'd lead to war between the empire and the homeworld gems, with the Crystal gems and rebellion caught in the middle.