They depend on the production method. All lapel pins start out as plain metal. Two different production types are soft enamel (die struck, the most common type of lapel pins) and hard enamel (or cloisonné - a highly polished, more jewelry like smooth finish).
It comes down to a preference for more pronounced raised and recessed areas or a smoother jewelry-like finish. Please send us information about your project - we can usually work with most any budget.