Platinum Art Deco Opal and Diamond Navette Brooch

A navette-form platinum brooch centering a large oval white opal cabochon displaying strong broad-flash play-of-color across the full face — red, orange, green, and blue in shifting patches — bezel-set within a milgrain-edged frame. Above and below the opal, the platinum is pierced and engraved with a running wheat or laurel leaf motif, a hallmark of Edwardian-to-Deco transitional craftsmanship. The pointed terminals flare into stepped, openwork panels each set with three old European-cut diamonds in milgrain collets. The combination of naturalistic pierced engraving with the clean geometric terminals places this squarely at the Edwardian-to-Art Deco transition, approximately 1915–1925.

• Era: Art Deco / Edwardian transition, approx. 1915–1925
• Metal: Platinum (appears; confirm hallmark)
• Center stone: White opal, oval cabochon, broad-flash play-of-color, red/orange/green/blue; approx. 12 x 28 mm (confirm)
• Accent diamonds: Old European-cut, milgrain collet-set, 6 stones total, approx.
• .30ct. t.w. (confirm); appears H-I / SI (visual estimate)
• Setting: Bezel (opal); milgrain collet (diamonds)
• Style: Navette brooch, pierced and engraved wheat/laurel surround, openwork terminals
• Closure: Roll-over C-catch pin stem (confirm catch type on reverse)
• Measurements: Approx.  17 mm x  37  mm overall (confirm)
• Weight: Approx. 3.6 dwt. (confirm)