The Affair of the Diamond Necklace (French: Affaire du collier de la reine, "Affair of the Queen's Necklace") was an incident from 1784 to 1785 at the court of King Louis XVI of France that involved his wife, Queen Marie Antoinette.
The Queen's reputation, already tarnished by gossip, was further sullied by the false accusation that she had participated in a crime to defraud the Crown's jewellers in acquiring a very expensive diamond necklace she then refused to pay for. In reality, she rejected the idea of buying it only to have her signature forged by Jeanne de Valois-Saint-Rémy. Although Jeanne was later convicted, the event remains historically significant as one of many that led to the French disillusionment with the monarchy, in that it was one of the contemporary scandals that gave moral weight and popular support for the French Revolution.