I'm reading this series because I watched the anime and remember liking it. My consistent complaint with manga is that it struggles to add the same depth to a story that I get from well written prose, and that holds here too. I found the very sparse palette of 5 or so tones in black and white made it hard to understand the images in some places, and I don't think it fits the setting's vibrant gemstone people. That said, I do really like the story, and technical immortality while you slowly watch your memories erode with your stone body is an intense tragedy that I think the author captures pretty well. If you like reading over watching a show, they're a quick enough read that I think it's worth picking up from the library.