The final process is called tempering. Uncontrolled crystallization of cacao butter typically results in crystals of varying size, some or all large enough to be cleariy seen with the naked eye. This cause the surface of the chocolate to appear mottled and matte, and cause the chocolate to crumble rather than snap when broken. The uniform sheen and crisp bite of properly processed chocolate are the result of consistently small cocoa butter crystals produced by the tempering process. The fate in cocoa butter can crystallize in six different forms (polymorphous crystallization). The primary purpose of tempering is to assure that only the best form is present. The six different crystal forms have different properties. As a solid piece of chocolate, the cocoa butter fat particles are in a crystalline rigid structure that gives the chocolate its solid appearance. Once heated, the crystals of the polymorphic cocoa butter are able to break apart from the rigid structure and allow the chocolate to obtain a more fluid consistency as the temperature increases the melting process. When the heat in removed, the cocoa butter crystals become rigid again and come closer together, allowing the chocolate to solidify.