1.33 Ct. Blue Sapphire from Ceylon (Sri Lanka)

This loose natural round blue sapphire from Ceylon offers a compact and highly considered specification for the connoisseur. The stone weighs 1.33 carats, and measures 6.21 by 6.16 by 4.42 millimeters, giving an average table diameter close to 6.19 millimeters and a depth that works out to approximately 71.5 percent. The cutting style is faceted with a mixed brilliant cut, meaning the crown is executed with brilliant type facets while the pavilion shows modified, precision oriented facets to optimize light return. Clarity is graded slightly included at face up viewing, which indicates fine internal features that are visible to the eye but do not significantly interrupt the overall light performance. Color is described as vivid, a saturated and pure blue typical of quality Ceylon material, and the surface finish is an excellent polish, producing crisp facet junctions and high mirror reflectivity. This sapphire has been heat treated, a standard and stable enhancement for Ceylon stones that improves color saturation and reduces certain types of inclusions, a treatment disclosed and consistent with the provenance recorded by The Natural Sapphire Company.

From a cutting and optical engineering standpoint the mixed brilliant cut chosen for this stone is purpose driven. Sapphires have a refractive index in the range commonly quoted for corundum, and a relatively low dispersion compared to gemstones such as diamond, therefore the cutter must prioritize strong contrast and well defined flashes over fire. The brilliant style crown produces numerous small, mirror like planes that contribute to lively scintillation, while the modified pavilion facets are set at angles that favor efficient light return in the face up position. The depth at approximately 71.5 percent is on the deeper side when compared to typical round brilliant proportions for colorless gems, but for a vivid blue sapphire this depth helps to intensify body color without producing a window. The excellent polish and precise facet symmetry minimize light leakage at facet junctions, creating a crisp, star like pattern of return when the gem is rotated under directional lighting. Because corundum transmits and absorbs light differently across the blue spectrum, careful facet design is essential to balance saturation and brightness, and this mixed brilliant faceting achieves that balance.

When assessing reflective qualities relative to other sapphires and related blue gemstones, a few consistent comparisons are useful. Kashmir sapphires are often associated with a velvety, diffused glow due to abundant microscopic silk and slightly softer facet reflections, and they exhibit less mirror like flash and more internal diffusion when compared to our specimen. Burmese sapphires tend to show strong, saturated color and excellent luster with similarly crisp facet reflections, often producing bold and evenly distributed light return, whereas Madagascan stones are variable, some showing very high brilliance after precise cutting, others presenting more windowing if cut shallow. Australian dark blue sapphires usually show strong luster but have greener or inky overtones that reduce perceived brightness. Compared to spinel of similar hue, this sapphire has a higher refractive index and therefore a stronger contrast between light and dark facet areas, which enhances scintillation even though dispersion is lower than that of diamond. The heat treatment performed on this Ceylon sapphire improves internal clarity and color homogeneity, which in turn sharpens reflective contrasts and increases visual depth when compared to untreated rough material of similar hue.

For practical use and design integration the gem’s optical profile suggests certain settings and considerations to maximize its face up presence. A setting that allows light to enter the pavilion and return to the viewer will emphasize the stone’s vividity and crisp scintillation, with open prong or low bezel designs recommended over fully closed bezel work that can dampen light return. The slightly included clarity implies that inclusions are present but not structurally compromising, and the excellent polish reduces surface scattering so reflections remain sharp. In everyday lighting the mixed brilliant faceting produces a lively interplay of flashes and darker contrast zones, and under focused directional light the sparkle is particularly dynamic due to the tight crown facet arrangement. When compared to the soft, glowing character of Kashmir material, this Ceylon stone reads as more lively and reflective, and compared to darker Australian material it retains greater brightness and color purity. The Natural Sapphire Company stands behind the gemological details and craftsmanship of this sapphire, and our specialists can advise on mounting options that will best exploit its cutting geometry, depth profile, and vivid Ceylon blue to deliver maximum visual impact.