Sterling silver ring stamped 925. Amethyst baguette center stone with three marcasite side stones each side. This is a square edge ring typical of the Art Deco era (1920's-1930's). The time between wars. Art Deco, also called style moderne, movement in the decorative arts and architecture that originated in the 1920s and developed into a major style in western Europe and the United States during the 1930s. Its name was derived from the Exposition Internationale des Arts Décoratifs et Industriels Modernes, held in Paris in 1925, where the style was first exhibited.