Period Carnival Glass Bat Hat PinPeriod authentic carnival glass pin. Originally a hatpin. Set in sterling silver pre 1950. A most interesting hat pin with a striking shape. Many carnival glass hat pins were made in Czechoslovakia, but we are uncertain of the origin of this pin. 2 inches. Carnival glass is moulded or pressed glass, always with a pattern and always with a shiny, metallic, 'iridescent' surface shimmer. Carnival glass gets its iridescent sheen from the application of metallic salts while the glass is still hot from the pressing. A final firing of the glass brings out the iridescent properties of the salts, giving carnival glass the distinct shine it is known for.