Possible Clues:

• Brief appearance came to nothing
• Famous actor's small role
• With 13-Down, something 7-Down is famous for in his films
• Piece of jewellery; small role
• Item of jewellery with a portrait - distinguished actor's minor role
• Short piece arrived with ring attached
• Small part's arrived - nothing more
• Gem carved in relief
• Showed up with nothing for gemstone
• A gem carved in relief