0.90 Ct. Bi Color / Parti Sapphire from Ceylon (Sri Lanka)

This sapphire's journey begins in the metamorphic host rocks of Ceylon, Sri Lanka, where late stage hydrothermal fluids concentrated chromium traces and iron titanium complexes within corundum. The rough that entered our workshop exhibited the classic indicators of Sri Lankan parti and bi color material, with discrete color zoning and pleochroic behavior visible to the loupe. The piece weighed slightly more in its rough state than the finished 0.90 carat, and its proportions suggested an optimal yield as a cushion shaped stone. The decision to pursue a faceted, mixed brilliant treatment was made after orientation studies under fiber optic lighting, with particular attention paid to preserving the bi color transition and to maximizing the intense color intensity that the rough demonstrated. Inclusions were present but minor at eye level, classified as very slightly included, and these were evaluated for their potential to act as light modifiers rather than detractors, guiding the cutting plan toward facets that would diffuse internal reflections and enhance overall transparency.

The cutting process was executed with exacting control over pavilion depth, crown angles, and facet junction crispness, informed by the refractive index and dispersion characteristics of corundum, approximately 1.762 to 1.770. The cushion outline was maintained with careful curvature of the girdle to balance visual weight and optical performance, producing finished dimensions of 6.27 by 4.68 by 3.36 mm. The mixed brilliant approach combines a brilliant facet arrangement on the crown with a modified pavilion structure, creating a balance between scintillation and color concentration. Crown facets were cut to angles that favor return of blue and yellow green pleochroic components depending on viewing axis, while pavilion facets were shaped to reduce windowing and to enhance internal light return, ensuring that the intense color intensity remains apparent in hand and under standard grading lamp illumination. The cutter targeted facet junctions with acute polish, achieving an excellent polish grade that minimizes light scattering and preserves clean facet reflections.

Post cutting, the stone underwent a controlled heat treatment, the industry standard for Ceylon sapphires, applied to stabilize and intensify hue and saturation. Heat treatment reduced silk and minor inclusions without altering the crystalline integrity, resulting in improved transparency and a more vivid expression of the bi color zoning. Color grading was conducted using comparable master stones, assessing hue, tone, and saturation, and the stone registers as having intense saturation with a dynamic bi color character that shifts between deep cornflower blue and a lighter yellow green, depending on orientation and lighting conditions. The mixed brilliant cut plays an important role in how those hues manifest to the viewer. Facet design was chosen to accentuate the stone's pleochroism, allowing the crown to reflect a rich blue flash while the pavilion returns warmer green to yellow notes when tilted. Clarity assessment at eye level confirms very slightly included, with inclusions that are internal and do not impinge on durability, and polish evaluation confirms an excellent finish with crisp facet edges and consistent symmetry.

From bench to market the stone was documented, photographed and cataloged by The Natural Sapphire Company, with provenance recorded as Ceylon, Sri Lanka, and enhancement noted as heat treated. The final presentation emphasizes both its gemological credentials and its practical considerations for setting. For jewelry design, orientation in the setting is critical to showcase the parti effect, and designs that allow rotation or incorporate open backed settings will permit the stone to display its full range of color and light performance. Mounting recommendations include low profile bezel settings for protection without suppressing color, or prong settings that allow light entry from both crown and pavilion for maximum scintillation. Care guidance reflects the heat treated nature of the stone, recommending avoidance of sudden thermal shocks and caution with mechanical steam cleaning, while noting that routine cleaning with mild detergent and a soft brush will maintain brilliance. The Natural Sapphire Company stands ready to provide certification documentation, precise measurements, and bespoke mounting options, ensuring that this 0.90 carat cushion shape bi color parti sapphire arrives to the market with complete technical transparency, and with the craftsmanship context that knowledgeable buyers expect.