Metal Necklaces: There could be light scratches or minor nicks on the chain or pendant. For plated metals, there might be some areas where the plating has faded or tarnished.
Clasp Wear: The clasp might not be as springy as it once was, or it might not close quite as securely.
Discoloration: Depending on the metal, the necklace might develop a slight patina or darkening over time. This can happen with silver necklaces, for example.
Enamel Imperfections: Enamel fill may have some minor chips, dents or air bubbles. You might also see some minor color bleeding or discoloration, dulling, especially on lighter colored enamels.
Stone or Bead Necklaces: The settings might loosen slightly, or some stones might have minor chips or scratches. Pearls can lose some luster.
String or Thread Necklaces: The string or thread might fray or break with moderate wear. This is especially true for delicate materials like silk or cotton.