From Introduction:

Crystalmancy - Powers of the Gems explains the mysterious powers behind these arcane spellcasters who carry with them a king's fortune in gems, and how they use these crystals and gems to perform amazing feats of arcane might that rivals any wizard or sorcerer. Chapter 1 shows two different ways to introduce crystalmancy into your campaign. One is as the Crystalmancer core class, much akin to the wizard, and the other as a prestige class for the wizards and sorcerers who wish to head down the road of crystalmancy. Also in chapter 1 are two new feats for all spellcasters, but most suited for crystalmancers and all other information on making crystalmancer characters.

Chapter 2 introduces a collection of new spells that have been crafted and discovered by crystalmancers in the past, but are just as easily used by other arcane spellcasters. Chapter 3 shows the true power that is at a crystalmancer's disposal: magic items. Avariety of minor, medium, major, and artifact level items are found in this chapter, all of which could easily be found in any campaign setting, doubly so in the presence of crystalmancers.

In chapter 4 introduces the surreal Plane of Crystal. Also known as the crystalline realm, it is a small world that is oddly similar to a normal world, yet everything is made of solid, multi-colored crystal. This chapter outlines the physical traits of the plane and provides information on several key locations and personalities, as well as tips on adventures to run in conjunction with this plane. Also found in chapter 4 are the Crystal Keepers. The Crystal Keepers are an organization of good-natured crystalmancers that try to extend the reach of the crystal path. Detailed are information on the organization, and information on the five powerful crystal lords who run the organization.

Chapter 5 unveils several new creatures related to crystals and crystalmancy, such as the crystal golem, gem bones, and the powerful gem dragon. The berylis, a crystalline race of people found in the crystal realm are also detailed here.

This volume aims to present a colorful new arcane class that can be used in nearly any fantasy setting. However, practically all of the information provided here can be used, sans the crystalmancers, if that is more fitting to your campaign setting. Perhaps the magic of crystalmancy is long-gone from the world, and only the remnants of their ancient spells and magical constructs remain to tell the tales.