The brooch (safety pin or fibula) formed one of the most frequent and distinctive features of changing Etruscan dress, fashion, and jewelry. The violin bow fibula was developed from the preceding pin fashion during the later Bronze Age, evolving in time into the serpentine elaborations of the bow. During the eighth century BC, a fashion for a leech shaped (sanguisuga) swollen bow developed, that in turn became a boat form (navicella) as the closed leech shape was opened up to form a shape similar to the hull of a ship. From the seventh century BC, the use of precious metals, particularly gold, became more frequent. The enlargement of parts of the fibula such as the catchplate gave opportunities for elaborate use of granulation and other goldsmithing skills. In the course of the sixth century BC, a new Certosa form with a distinctive button on the catchplate was developed. Many variations of these forms allow dating with some precision of individual finds, and in closed contexts the variations aid in the dating of the deposit where they were found.
Historical Dictionary of the Etruscans. Simon K. F. Stoddart.