Platinum French Balloon Sapphire and Old Mine Cut Diamond Brooch Circa 1890's

Platinum finely crafted French ‘balloon’ brooch, measuring approximately 3.5 inches in length, with obscured French hallmarks. The central natural blue cabochon star sapphire ‘balloon’ measures approximately 15.1mm x 13.2mm x 11.15mm (weight estimated to be 13.50 carats), and exhibits a light slightly grayish-blue hue, with well-defined star under a focused light source. Accompanied by GIA Report, stating that the sapphire exhibits no indication of heating, and is from Sri Lanka. Circa 1890's