This is a vintage Royal Copenhagen porcelain pin or trinket dish, or possibly an ashtray, featuring the "Marmorbroen" (Marble Bridge) design. 

• Manufacturer: Royal Copenhagen, Denmark.

• Item Number: The hand-painted number on the back is 3302.

• Quality Mark: The three blue wavy lines are the signature mark of Royal Copenhagen.

• Design: The specific design depicts the Marble Bridge in Copenhagen, Denmark.

• Material: It is made of fine, hand-painted porcelain.