1.58 Ct. Blue Sapphire from Ceylon (Sri Lanka)

One transparent cushion shape blue sapphire weighing 1.58 carats, measuring 6.91 by 6.91 by 4.14 millimeters, is presented from Ceylon Sri Lanka, offered by The Natural Sapphire Company. The gem is faceted with a mixed brilliant cutting style, combining a brilliant facet arrangement on the crown with stepped pavilion elements, executed to a high standard. Color assessment registers as intense, with even saturation across the table and crown facets, and clarity has been evaluated as eye clean at standard viewing distance, with no interruptions to visual performance. The stone has undergone routine heat treatment to enhance color homogeneity and diminish microscopic inclusions, a stable and accepted enhancement for corundum, and the surface finish is described as excellent polish, with crisply defined facet junctions and consistent facet symmetry across the girdle.

The cutter allocated proportional dimensions to balance color depth and light return, resulting in a depth of approximately sixty percent relative to the table span, a proportion that optimizes both face up color and internal brilliance. The mixed brilliant approach uses smaller crown facets to generate tight scintillation and lively pinfire, while the stepped pavilion controls color zoning and strengthens face up intensity. Facet geometry emphasizes precise angles to match corundum refractive indices near 1.76 to 1.77, reducing light loss through windowing and promoting internal reflection. Birefringence in corundum is low, so doubling effects are minimal, yet the material displays pleochroism, typically showing a primary cornflower blue and a secondary cooler violet blue on different optical orientations, a characteristic exploited by the cutter to present the most attractive hue face up.

Optical behavior under varied lighting conditions is consistent with a well cut Ceylon sapphire with intense saturation and excellent polish. In bright daylight and direct sunlight the gem exhibits lively brilliance and a strong face up cornflower blue, with flashes of lighter blue to near white appearing from the small brilliant crown facets, and a steady deep undertone from the pavilion retention. Under cool white LED sources the hue reads as true, slightly higher in chroma, with crisp contrast between bright facet flashes and saturated body color, making facet outlines appear more distinct. Under warm incandescent or halogen illumination the stone shifts subtly toward a deeper, more velvety blue with a hint of violet, enhancing perceived depth and softening pinfire in favor of larger scintillation flashes. Fluorescent lighting can slightly desaturate weaker stones, however the strong intrinsic saturation of this sample resists washing out, retaining a rich face up blue. In low light and candlelight the sapphire moves to a richer, more subdued blue with reduced scintillation but greater apparent depth, offering a classic nocturnal presence. The combination of mixed brilliant cutting, excellent polish, and eye clean clarity ensures that this 1.58 carat cushion sapphire will perform with consistent brilliance and color vividness in a variety of settings, and The Natural Sapphire Company recommends settings that allow light to enter through the pavilion for maximum performance.