A style of setting a gemstone in a finger ring in which the stone is placed in a collet of reflective and brightly burnished metal, and then the metal edges are cut or shaped so that, when bent aroundthe stone, they create the illusion of being a part of the stone. Such a setting is used mainly for a small diamond so as to enhance its apparent size.The style was invented by the French jeweller Oscar Massin in the 1860s. The French term is 'monture illusion' also called a 'deceptive setting' or a 'mirage setting'.