Exceptional vintage Art Deco convertible Duette brooch signed MAZER, featuring an elaborate geometric fan-shaped design adorned with sparkling clear faceted glass rhinestones. The intricate openwork construction incorporates closely arranged pavé-style rhinestone detailing, angular geometric patterns, and elongated baguette-style accents. The silver-tone metal features a brilliant, rhodium-like finish, although the exact plating composition has not been verified. Measuring approximately 2.25 inches wide by 1.25 inches tall, this elegant piece showcases the sophisticated craftsmanship and Old Hollywood glamour associated with late 1930s–1940s designer costume jewelry.

The reverse bears the MAZER manufacturer's signature and U.S. Patent 2,143,538, corresponding to a convertible brooch mechanism invented by renowned jewelry designer Marcel Boucher. The patent was filed October 10, 1935, and granted January 10, 1939, during the period of Boucher's association with Mazer Brothers. Before his American costume jewelry career, Boucher worked for Cartier, bringing experience in fine-jewelry design to the industry. The patented construction allows the brooch to be separated into two individual decorative dress clips, making this a versatile and historically interesting example of signed Mazer jewelry. The patent identifies the mechanism's inventor and does not independently establish the designer of the decorative front.

Vintage pre-owned condition with age-related surface wear, light scratches, and some discoloration or yellowing to individual rhinestones. The piece retains its two dress clips and brooch assembly, as shown in the photographs. A distinctive addition to a collection of signed Mazer Brothers jewelry, Art Deco rhinestone brooches, or vintage convertible dress clips. Suitable for collectors, vintage bridal accessories, and Old Hollywood-inspired styling. Please examine all photographs carefully for condition, construction, and details.