I have to say that John Vornholt is not one of my favorite Star Trek writers, so I started reading this duology called Gemworld with a little trepidation. I was mildly surprised. The writing was at a higher level than the last book I read by him (I can't remember which book that was), although it didn't pass into spectacular. But was really surprised me was the actual plot elements and the detail of the world he created here.
The books focus on the remains of an ancient water world, where the water has mostly evaporated away, leaving behind crystalline structures with liguid marrow trapped inside and an atmosphere held in place by a lattice of forcefields. The mass of the planet is so low that it basically has no gravity. I don't have enough of a science background to know whether this setup is even possible, but it was intriguing enough to hold my attention.
In any case, something has happened and now mutant crystal is growing at an increasing rate, threatening to destroy the entire planet. Melora, one of the inhabitants of the planet who has joined Star Fleet (and who first appeared in an episode of Deep Space Nine), and Deanna receive a dream distress call and the Enterprise sidetracks to investigate.
Upon their arrival, they are immediately nearly destroyed by a mysterious dimensional rift that doesn't appear on their sensors, but it spewing dark matter toward the planet, which the massive shield that keeps the planet in one piece uses to help keep its inhabitants alive. The problem is that there's too much dark matter, and the shield is converting the excess into the mutant crystal. But no one can figure out why.
The story unfolds from there. The best aspect of the two books is the world itself and the inhabitants. Having no gravity except on the Enterprise and its shuttles gives an interesting twist to the investigation. Having the Enterprise and its shuttles flying about in atmosphere, with the crew able to work on repairs and learn about the world without the need of spacesuits was also interesting. As pointed out in the book, this would be a perfect starbase. So in the "oh, cool" scale, the books have a huge wow factor that sparks the imagination.
My problems with the book, which I overlooked while reading because of the wow factor, all have to do with the writing. Some of the key plot elements are "discovered" so much as stated or asserted. For example, the dimensional rift. There was never an investigation into what was generating the dark matter, and it was sain repeatedly that the rift didn't register on their sensors . . . so how did they know what it was? How did they know it led to another dimension? There were a few other elements like this in the books. It would have been simple to fix something like this, and I don't see why that wasn't done. Most of the character's emotional states were also just stated, rather than shown, which made the emotional content of the book kind of flat. I didn't like the "romance" aspects of the book either, especially in book 2. Not that I don't like romance elements, but it just felt somewhat cheesy.
But as I said, the wow factor is great enough that you can overlook, or at least "overread", these other aspects. There's a good plot here overall, with plenty of twists and turns, especially in book 2. (Book 1 is mostly setup.) Not the greatest Star Trek books I've ever read, but definitely fun.