Not expecting anyone to read this but...
I just watched Hayao Miyazaki's masterful Castle in the Sky and I couldn't help but notice some parallels to this.
I love this anime. I rented the title from Blockbuster about 4 or five times until they sold off all of their vhs tapes and I was lucky enough to purchase them.
BUT Castle in the Sky features a girl w/ a powerful crystal accompanied by a ragish boy, a group of space pirates lead by a woman, military ships on hot pursuit and an overall costume and setting design that recalled this. But Castle came out in 1986.
I was hoping I wasn't the only person in the world who likes Legend of the Crystals, but if anyone reads this, I would like to know if you noticed the inspiration a little.
"But, Captain, wouldn't it be more humane-like to slit his throat?"