First off I'll say that the concept of the gems and their bodies makes for some fantastic imagery and ideas. People can be fixed, but if the parts don't match the original, there's a chance of losing your memories. In episode 2, one particular moment with the slug king makes for a downright unnerving experience when we get to see a gem melt away, and the constant occurrences of gems cracking reminds you that these creatures are far from human.
So why, I'll ask, do the gems look and act so human? This is hinted at in the story (by the slug king when it talks about the history of the world), but I can only wonder what this show would have been if the characters were designed to be something truly alien. Human-like characters are easy to identify with, sure - even more so when they look like anime girls for an anime audience, but personally I think this is taking the easy route. Kemono Friends turned every animal into a talking anime girl that barely acted like the animal they represented. Lustrous doesn't go quite so far, because gems are a new species entirely, but to any outsider looking in, these characters usually look and behave like nothing more than your average anime chick, just with more sparkly hair. Gems, as the story explains, are genderless. So why make their appearances and voices overwhelmingly female? (Except master Kongou - obviously the best waifu here.)
At the end of the day this is personal preference, but I've always appreciated when a story goes all out on its fantasy elements. Take the Jokka: a species that can change between 3 sexes, cry from their fangs (female tears are poisonous), have white-colored blood, and act under some very questionable moralities and beliefs. All that, and they're still understandable and sympathetic characters by the end of the books. It leaves me to wonder what the gems could've been if they were more science fiction and less... 'anime'. (Still better than kemono friends though)
Speaking of kemono friends - CG animation. Lustrous looks damn good. It's rare to find something fully CG that looks this good, but you tend to forget the show was even animated in such a way. The sparkly hair and internal makeup of the gems compliment the CG, and the action looks fluid and clean. I can't say I prefer this over good old 2D drawings, or that everything blends well, but Lustrous does a great job with its CG and that's something to be appreciated for sure.
In terms of story, my favorite aspect of this show is its mysteries. Lustrous makes you questions things like why the Lunarians are taking the gems, and just what the Lunarians are. The design and theme of the Lunarians seem to be straight out of Buddhism, and they make for an interesting enemy reminiscent of the angels from Eva - or for a better comparison: the invaders from Shangri-La in Noein. Overall Lustrous does a great job of making you want to learn more about the world and its history, even if that history isn't fully explored yet. There's lore, and there's history, and it brings the world to life the more of it we get to see.
The characters are a bit of a mixed bag. Phos undergoes a powerful transformation and grows. Between episodes 8 and 9, this change is so drastic it's both unrealistic and effectively sad to witness what they goes through. Phos can be annoying with their spunkiness, but I liked them and rooted for them to become stronger and pull through. Cinnibar seems promising, but in this first season they're little more than a tsundere and got far less screen time than I was expecting. Dia is excellent for one episode, then fades away until a couple scenes in episodes 10 and 11. Kongou is cool and mysterious, and works well as a father figure to the gems. Overall while I liked the characters, I think there were too many of them with not enough time spent on any one except Phos. The gems work well together, but I feel like the majority of them got left behind in the end. I have high hopes for the second season continuing their development, though.
The pacing in this series is excellent most of the time. It knows when to get serious and when to have lighter moments, and those lighter moments got some laughs out of me (like Kongou passing out and slamming his head into the wall so hard it cracks the rock). Sometimes I think it was too silly when it should have been serious, but this was rare.
Overall this was a solid (pun not intended) show based on uniqueness and memorability alone. It has a lot of elements (I swear I'm not doing this on purpose) to like, and gives an overall feeling of growth and transformation by the end, which is only possible in this setting because of what the characters and world are. Phos embodies this change, and they're no longer one part but an amalgamation of something bigger - a person moving toward better things. I'll be looking forward to what another season has to offer, but for now the series we've got could be considered a minor... gem... of a show.
Goodbye.
