The Amazon.com product description:
Her name was Killashandra Ree. And after ten grueling years of musical training, she was still without prospects. Until she heard of the mysterious Heptite Guild who could provide careers, security, and wealth beyond imagining. The problem was, few people who landed on Ballybran ever left. But to Killashandra the risks were acceptable....I first read the Crystal Singer trilogy back some time in the late 1990's and I've enjoyed it off and on since then. This book sets up the world quite well, with some very intriguing premises. I will say that the description doesn't say a heck of a lot about the story, though it does say quite a bit about the main character. But, that leaves plenty for you to discover as you read your way through all three books.
Crystal Singer is the first book, followed by Killashandra and Crystal Line (which I'm reading now). They're not overly long reads by today's standards, at just over 300 pages more or less, but although these books are over twenty years old (25+ for Crystal Singer), they've held up to the tests of time very well, at least in my opinion.
Personally, I quite like the way Anne McCaffrey has created this universe - though I'm still not sure if it's an entirely separate universe than some of her other books. None of they others make any mention of crystal for communications or other uses, but the Crystal Singer books do use the Brain/Brawn ships of the Brain Ships books.
Crystal Singer sets up the world quite nicely, making a complete story in itself. But, I think the best ones are the two books that follow this one.
Not the greatest books, I have to admit, but like Mercedes Lackey's stories these are books that I've been able to enjoy reading just for the escape factor.