Turn-pin spectacles were made during the entire 19th Century. Those made before 1833 were hand-made by jewelers. Turn-pin spectacles made after the introduction of the spectacle making machine in 1833 are machine made. It is my opinion that this style was not as popular or cost more to make. Fewer examples come to the marketplace. Also, many turn-pin are made from gold and silver. Such spectacles were more likely to be used by merchants, politicians, and individuals in a profession that required an education.