Art Deco Jewelry Markings (1920s-1940s): Identifying Platinum, White Gold, and Period Maker's Marks

Art Deco jewelry is defined by its geometric precision, architectural lines, and bold use of contrasting colors and materials. The movement drew inspiration from Cubism, Egyptian archaeology (particularly after the discovery of Tutankhamun's tomb in 1922), African and Asian art, and the machine age's celebration of speed and technology. Jewelry from this period features stepped forms, fan shapes, chevrons, sunburst motifs, and symmetrical patterns executed with extraordinary precision.

The hallmark of Art Deco craftsmanship is the integration of colored gemstones with diamonds in geometric arrangements. Calibre-cut rubies, sapphires, and emeralds were precision-cut to fit exactly into channel settings alongside brilliant-cut and baguette-cut diamonds. Black onyx, coral, jade, and lapis lazuli provided dramatic color contrasts. The metalwork itself was often pierced and milgrained, creating a lace-like openwork effect that required extraordinary skill. These design characteristics, combined with specific marking conventions, help authenticate Art Deco pieces.

Platinum dominated high-end Art Deco jewelry, prized for its strength, white color, and ability to be worked into extremely delicate settings. Platinum marks from this era include "PLAT," "PT," "950," and "PLATINUM." In France, platinum was marked with the dog's head hallmark (tete de chien) starting in 1912. British platinum hallmarking did not begin until 1975, so genuine Edwardian and Art Deco British platinum pieces lack an official platinum hallmark and were often marked "PLAT" or "PLATINUM" by the maker.

White gold emerged during the Art Deco period as a more affordable alternative to platinum, particularly after platinum was declared a strategic metal during World War I and its use in jewelry was restricted in some countries. Early white gold alloys used nickel as a whitening agent and were marked "18K" or "14K" with an additional white gold designation. The transition from platinum to white gold is itself a dating clue: pieces from the early 1920s are more likely platinum, while those from the 1930s and 1940s increasingly use white gold. Yellow gold returned to prominence in the late 1930s and 1940s Retro period, and pieces from this transitional era may combine white and yellow gold.

Several jewelry houses are synonymous with Art Deco design, and their maker's marks are highly prized. Cartier pieces from this era carry the "CARTIER" name stamp along with serial numbers and metal marks, typically "PT950" or "750." Van Cleef & Arpels used "VCA" or the full name, often accompanied by French assay marks including the eagle head for 18K gold and the dog's head for platinum. Boucheron, Mauboussin, and Lacloche Freres are other major French houses whose Art Deco work is museum-quality.

In the United States, Tiffany & Co. marked pieces with "TIFFANY & CO." alongside metal purity marks. Oscar Heyman & Brothers, a behind-the-scenes manufacturer for many top retailers, used "OH" or a specific maker's number. Raymond Yard, Black, Starr & Frost, and Marcus & Co. are among the American firms whose Art Deco pieces command premium prices. In Britain, makers like Garrard and Mappin & Webb produced distinctive Art Deco designs bearing their registered hallmarks alongside standard British assay marks.

Distinguishing platinum from white gold in Art Deco jewelry requires careful examination of the marks. Platinum pieces are heavier than gold of the same size due to platinum's higher density (21.45 g/cm3 versus 19.32 g/cm3 for pure gold). Platinum marks include "PLAT," "Pt," "950Pt," "PLATINUM," and in French pieces, the dog's head hallmark. Some early platinum pieces are marked "IRID PLAT" or "IRIDIUM PLATINUM," indicating a platinum-iridium alloy that was common in the period.

White gold marks follow standard gold marking conventions but may include additional designations. Look for "18KW," "14KW," "750WG," or simply the standard karat mark. Early white gold often has a slightly warmer tone than modern white gold because the alloys were different. Some Art Deco pieces originally made in white gold have been rhodium-plated at a later date to achieve a brighter white appearance, which can complicate identification. If the marks indicate gold but the piece appears platinum-white, the rhodium plating may be masking a warmer underlying metal.

The enduring popularity of Art Deco design has produced a steady stream of reproductions since the 1960s. Identifying these requires attention to both marks and construction. Modern reproductions typically carry contemporary hallmarks and maker's marks that, when researched, reveal a manufacturing date decades after the Art Deco period. A piece marked with a post-1975 British platinum hallmark, for example, cannot be an original Art Deco piece.

Construction details also distinguish originals from reproductions. Genuine Art Deco pieces were hand-fabricated or cast using lost-wax techniques of the period. The metalwork shows subtle irregularities under magnification that are absent in modern CAD-designed and machine-finished reproductions. Original Art Deco calibre-cut gemstones were individually hand-cut to fit specific settings, while modern reproductions often use standardized machine-cut stones. Examine the backs and undersides of pieces: original Art Deco work typically has hand-finished galleries and open metalwork, while reproductions may show modern casting marks or simplified construction.

Patina and wear are additional clues. A genuine 1920s brooch will show 100 years of natural wear on its catch mechanism, pin stem, and high points. Wear should be consistent across the piece. If the front shows heavy wear but the marks are crisp and unworn, the markings may have been added or altered. Provenance documentation, original boxes, and period receipts add significant confidence to authenticity claims, though these too can be fabricated. For high-value Art Deco pieces, independent authentication by a specialist gemological laboratory or auction house expert is strongly recommended.