39.04 Ct. Grey Sapphire Crystal from Ceylon (Sri Lanka)

This specimen is a semi transparent grey sapphire weighing 39.04 carat, with overall dimensions of 24.20 x 17.80 x 13.90 mm, presented in a various shape rough crystal cut. The piece exhibits natural crystal terminations and planar faces, with selected surfaces showing an excellent polish that enhances the stone surface luster. The body color is a light intensity grey that reads as a cool neutral to slightly warm grey under daylight, and translucency is sufficient to allow internal light transmission while preserving a soft veil of color. As corundum, the chemistry is aluminium oxide, the refractive index sits in the typical sapphire range of approximately 1.762 to 1.770, birefringence is low at about 0.008, and the specific gravity is roughly 3.98 to 4.03, these metrics informing both lapidary strategy and gemological identification. The specimen is unenhanced, with no heat or other treatments applied, and it is documented as originating from Ceylon Sri Lanka, a provenance that often correlates with fine crystalline development and classical crystal habits.

Color and clarity characteristics are central to the way this rough will behave once set or faceted, the light color intensity of the grey tone is subtle, and internal features include growth zoning and some fine needle or silk inclusions that are typical for Sri Lankan material. These inclusions contribute to the body color through scattering, and they can accentuate a satiny or silky effect in certain cutting orientations. Grey sapphires commonly show weak pleochroism, changing slightly between colorless and bluish grey axes, and orientation is therefore a critical variable during preforming to maximize the preferred hue and minimize undesirable windowing. The semi transparency and inclusion pattern advise a cutting approach that balances retention of weight with optical performance, because aggressive removal to eliminate all inclusions would markedly reduce carat weight. For collectors who value the natural crystal aesthetic, leaving significant facets of the original termination intact preserves specimen character while selective polishing can highlight natural geometry.

From a craftsmanship standpoint the rough crystal cut of this sapphire offers several attractive pathways. If the client desires a finished faceted gem, a conservative yield strategy would favor step cuts or mixed cuts that retain broad table areas and shallower pavilion depths, preserving up to fifty percent or more of the original weight depending on orientation and internal features. Alternatively, a freeform faceted design or an elongated cushion or oval can follow the existing crystal outline to maximize carat retention, while a cabochon or low dome could be the ideal choice for preserving internal chatoyancy or silk induced effects. Working this material begins with meticulous mapping under immersion to delineate inclusion positions and growth zoning, followed by sawing and preforming along the best optical axis. Grinding and shaping are executed on diamond laps with progressive grits, and final polish is achieved with diamond paste or cerium oxide depending on the lapidary surface and desired luster, the excellent polish already present on selected faces suggests minimal finishing will be required in those areas. Given the untreated status, cutting and polishing should proceed with conservative heat control, and a laboratory report is recommended to certify the unenhanced nature and Sri Lankan origin, factors that materially affect market valuation.

For the buyer and designer this 39.04 carat Sri Lankan grey sapphire presents distinct options, as a centerpiece for a bespoke pendant it will display its mass and subtle tonal complexity with minimal optical distraction, alternatively a carefully faceted version can produce a large, gently luminous table that reads as an elegant neutral grey in a high end ring setting. The lack of enhancement increases rarity and collecting appeal, especially for connoisseurs who prefer straight natural material. Care recommendations are straightforward, warm soapy water and a soft brush are the safest routine cleaners, mechanical ultrasonic and steam methods should be used with caution if internal inclusions create structural planes, and abrupt thermal shocks should be avoided to protect the internal fabric. At The Natural Sapphire Company we can provide detailed cutting plans and yield estimates, supply independent gemological documentation, and advise on mounting strategies that respect the crystal geometry while optimizing visual performance. If you require a tailored cutting proposal, setting recommendations, or further photomicrograph documentation, we will be pleased to assist with precise technical support and bespoke service.