In previous editions of the world’s oldest role-playing game, crystal dragons were the least of the gem dragons, the neutral (and psionic!) counterparts to chromatic and metallic dragons. So far, Pathfinder lacks both gem dragons and psionics, so the crystal dragon label instead lives on in the primal dragon sept. These are lawful, usually good-natured creatures who are also vain and quick to take offense. This may seem like a paradox, but any adventurer who has spent time around a royal court full of dandies or the upper ranks of an imperial navy will quickly recognize the type.
A magic staff requires the scale of a crystal dragon as a focus for its prismatic spray.
A crystal dragon and an umbral dragon war for territory in the depths of the Lands Below. The umbral dragon also employs morlock thralls to raid a nearby abandoned dwarf citadel for ancient magic and weapons. A tribe of mongrelmen rangers and rogues, excellent scouts and skirmishers all, could turn the tide, but the crystal dragon must be convinced to look past their hideous appearances.
Being lawful neutral, not all crystal dragons scorn the charms of Hell; some older specimens even choose to live there instead of the Plane of Earth. Their sonic breath affords them wide berth from the local devils, and their domains can thus be pockets of light (deep, cavernous pockets, to be sure) in the otherwise forbidding hellscape. Devils excel at flattery and persuasion, though, which means characters seeking sanctuary with a crystal dragon had best get the beast’s sworn oath to protect them, lest they find themselves handed over directly to the hamatulas by the apologetic, preening wyrm.
—Pathfinder Bestiary 2 98–99