The St. Christopher medal is the size of a penny and made in vermeil (gold plate over sterling silver) Please note that gold plating will wear over time. Avoid abrasive cleaning products, and cosmetics to extent its life. The necklace is made in gold-filled, which is a fine layer of gold that is bonded to a base metal. Gold filled jewelry will wear for years. The fob clasp is worn in front with the medal clipped on.