Disclosed are plastic preforms and bottles, preferably comprising polyethylene terephthalate (PET), in which the materials in the neck, neck finish and/or neck cylinder is at least partially in the crystalline state and the body is primarily in the amorphous or semi-crystalline state. This structure in a preform enables the preform to be easily blow molded by virtue of the amorphous material in the body, while being able to have dimensional stability in hot-fill applications. In addition, the amorphous inner surface of the neck finish stabilizes the post mold dimensions allowing closer molding tolerances than other crystallizing processes. On the other side, the crystallized outer surface supports the amorphous structure during high temperature filling of the container. Physical properties are also enhanced as a result of this unique crystalline/amorphous structure.