I have cast this cute button from an actual vintage button in solid bronze and sterling silver plated white bronze, it measures 20mm in diameter. I have suspended the pendant from an 18" necklace - antique bronze for the bronze version and a black gunmetal chain for the silver plated white bronze version.
Bronze and Silver Plated White Bronze
Bronze - 18" Antique Bronze Chain
Sterling Silver White Bronze - 18" Black Gunmetal Chain