Patek Philippe president Thierry Stern personally introduced the latest version of the brand’s successful Twenty-4 collection in Milan: the Twenty-4 Automatic. This is the first mechanical movement in a collection that has until now been powered by quartz and the first to feature a round case. Stern explained that the Twenty-4 Automatic has been five years and 40 prototypes in the making. Nancy Olson learns if it’s all been worthwhile.