0.37 Ct. Blue Sapphire from Ceylon (Sri Lanka)

This listing describes a single, transparent, round shape blue sapphire weighing 0.37 carat, with exact dimensions of 4.35 by 4.31 by 2.78 millimeters, originating from Ceylon Sri Lanka, and supplied by The Natural Sapphire Company. The stone is faceted in a mixed brilliant style, combining a brilliant facet arrangement on the crown with modified pavilion faceting to balance flash and depth of color. The clarity is assessed as very slightly included at eye level, and the gem has an excellent polish. Importantly, this sapphire is natural with no enhancement, retaining original crystal structure and coloration from the Sri Lankan deposit. The close dimensional tolerances and the precision of the mixed brilliant execution produce a face up presentation that maximizes apparent diameter relative to carat weight, while the measured depth of 2.78 millimeters corresponds to an overall depth percentage of approximately 64.3 percent based on the mean diameter, a proportion that favors both strong light return and even color saturation.

Optically the mixed brilliant cut in this piece is designed to produce a combination of bright return and controlled contrast. The brilliant crown facets act to fragment incident light into lively scintillation and return high level white light for perceived brilliance, while the pavilion’s modified facet geometry helps to direct deeper blue of the body color to the viewer, creating a layered visual effect. Under direct midday sunlight the sapphire displays strong contrast between intense, saturated flashes from the pavilion and glittering white specular highlights from the crown facets, the result is a lively, lively face up presence with a clear, medium intensity blue that reads distinctly as Ceylon blue rather than overly dark. In open shade and overcast daylight the stone moderates toward a softer medium tone, revealing more of the gem’s internal color zoning and allowing subtle pleochroic behavior to be observed as the stone is rotated, with slightly different blue vectors becoming perceptible between table up and pavilion up orientations.

In artificial lighting the behavior shifts in predictable, useful ways for design and daily wear considerations. Under warm incandescent or halogen sources the blue takes on a richer, slightly warmed aspect, with increased perceived depth and a subtle enhancement of the midtones due to the higher red component of the light source. Under cool white LED lighting the sapphire emphasizes its blue primary, delivering crisp blue flashes and making the stone appear slightly brighter and more vivid at the table. In low light or candlelight the mixed brilliant geometry preserves small pinpoints of scintillation and retains a pleasing blue presence even when overall brightness drops, because the pavilion angles are tuned to return light efficiently rather than leak it away. The gem’s very slightly included grade means internal features are minimal and positioned such that they generally do not interrupt facet-to-facet light paths; in practical terms the inclusions are not visually distracting in normal viewing conditions and they do not materially degrade the stone’s ability to perform optically across lighting environments.

From a craftsmanship and setting perspective, this untreated Ceylon sapphire benefits from the excellent polish and proportioning applied during cutting, which results in crisp facet junctions and controlled facet faces that enhance both brilliance and color uniformity. The 0.37 carat weight and near-equal diameters make this an ideal candidate for a delicate solitaire, a precision halo companion stone, or a bezel set accent where the medium color intensity will provide a stable chromatic anchor without overpowering adjacent gems. White metals such as platinum or white gold will emphasize the gem’s cool blue character and maximize perceived brilliance, whereas a warm mounting such as yellow gold will subtly intensify the apparent body tone and convey a richer, vintage warmth. Because this sapphire is unenhanced, its natural Ceylon color will respond predictably to different metal tones and lighting conditions without the variability introduced by surface coatings or diffusion treatments. The Natural Sapphire Company stands behind the provenance and untreated status of this gem, and we recommend considering the stone in settings that allow both table up light exposure for daytime sparkle and angled light access to exploit the mixed brilliant cut’s dynamic scintillation. If you would like further technical measurements, facet diagrams, or comparison images for setting visualization, we can provide them upon request.