Fabulous Art Deco Platinum, Star Sapphire & Diamond Brooch by Grogan & Co of Philadelphia

An extraordinary example of Art Deco jewelry design, this magnificent platinum brooch by Grogan & Co. of Philadelphia showcases the geometric elegance, exceptional craftsmanship, and luxurious gemstones that defined the 1920s. Dating to circa 1925, the brooch features an impressive 18.70-carat cabochon star sapphire surrounded by approximately 3.00 carats of brilliant diamonds, all arranged within an elongated, openwork platinum setting. The sapphire displays a beautiful, soft violet-blue hue, and its smooth, domed surface contrasts sharply with the brilliance of the surrounding diamonds. The brooch's dramatic silhouette combines sharply defined geometric borders with delicate linear detailing, creating a sophisticated composition that perfectly captures the Art Deco movement's architectural influence. With its remarkable proportions, prestigious maker, and exquisite combination of color and sparkle, this piece represents the artistry and refinement of fine American jewelry from the early twentieth century.

At the center of the design rests a substantial 18.70-carat star sapphire, polished into a rounded cabochon to highlight the gemstone's distinctive optical character. Star sapphires are prized for asterism, in which fine, needle-like inclusions within the stone reflect light to produce a luminous, star-shaped pattern under directional illumination. An angular, diamond-set platinum surround frames the sapphire, following its softly rounded outline while introducing the crisp geometry characteristic of the Art Deco period. Symmetrical openwork sections extend above and below the centerpiece, each featuring a graduated arrangement of round diamonds suspended along the central axis. Additional diamonds trace the elongated outer borders, creating continuous lines of brilliance that emphasize the brooch's elegant proportions. The approximately 3.00 carats of diamonds are graded VS clarity and H–I color, offering exceptional sparkle against the cool white platinum setting. Fine platinum crossbars and delicate structural details give the piece an airy appearance, letting light and negative space become integral elements of the design. The precisely arranged diamonds, architectural symmetry, and softly glowing sapphire create a beautifully balanced composition with remarkable visual depth.

Founded in Philadelphia, Grogan & Co. was an American jeweler known for fine jewelry, silver, and luxury goods in the late nineteenth and early twentieth centuries. The firm's craftsmanship and sophisticated designs reflected the tastes of an affluent clientele, making surviving signed examples particularly appealing to collectors of historic American jewelry. This circa-1925 brooch beautifully illustrates the transition toward the bold geometry and streamlined elegance that characterized the Art Deco era, while retaining the intricate hand-finished details associated with earlier platinum jewelry. Its elongated silhouette recalls the period's architectural forms and decorative symmetry, while the exceptional star sapphire introduces a softer, more organic focal point. The generous diamond coverage and substantial gemstone presence make this an especially impressive example of period jewelry, equally suited to a distinguished collection or as a dramatic statement accessory. Combining an important American maker, a remarkable 18.70-carat star sapphire, and approximately 3.00 carats of diamonds in an intricately constructed platinum mounting, this brooch is a captivating testament to the luxury and artistic innovation of the Roaring Twenties.

Details: Antique Art Deco brooch by Grogan & Co. of Philadelphia, crafted in platinum circa 1925, featuring an 18.70-carat cabochon star sapphire accented by approximately 3.00 carats total weight of diamonds graded VS clarity and H–I color, with an elongated geometric openwork design and diamond-set borders.