3.18 Ct. Blue Sapphire from Ceylon (Sri Lanka)

This 3.18 carat Ceylon blue sapphire from The Natural Sapphire Company presents as a transparent, well-proportioned oval measuring 9.79 by 7.26 by 5.07 millimeters, a length to width ratio of 1.35 that balances presence with wearability for ring and pendant applications. The cutter executed a mixed brilliant design, marrying a traditional brilliant-style crown with a modified pavilion to maximize return of light while reducing windowing and excessive extinction. The pavilion depth relative to average diameter is approximately 59.5 percent, a proportion that sits squarely within the empirically preferred range for corundum and supports full, lively face-up brilliance without sacrificing apparent size. The stone has been heat treated, a stable and industry-standard enhancement for Sri Lankan sapphires, and exhibits an excellent polish that produces crisp facet junctions and strong contrast facets under direct light.

From a faceting and optical engineering perspective, the mixed brilliant format used here is deliberately chosen to exploit sapphire’s high refractive index and strong dispersion. The crown’s brilliant facet arrangement disperses white light into discrete flashes while the modified brilliant pavilion, with its combination of kite and star facets transitioning into modified pavillion facets, controls the internal light path so that reflections are returned to the viewer rather than lost as windowing. The oval outline has been cut with careful attention to symmetry to maintain even light performance across the table and shoulders; minor adjustments to crown height and table dimension have been made to tune the spread versus depth ratio so the stone reads larger face-up than its carat weight alone would suggest. The excellent polish is evident in the clean facet planes and sharp facet edges, which contribute to a high degree of scintillation and allow the medium intense color to present uniformly across the face.

Color and clarity are central to the character of this Ceylon sapphire. The gem is graded as medium intense in color intensity, a saturation level that occupies the highly desirable middle ground between muted pastel tones and overly dark stones. The hue is a pure blue with subtle variances typical of Sri Lankan material, where slight secondary violet undertones can occur but do not dominate; color distribution is even with minimal zoning, allowing the stone to deliver a lively, saturated appearance under daylight and artificial illumination. Clarity is described as very slightly included at eye level, indicating small internal features that are discernible to a trained viewer under normal inspection but do not materially detract from transparency or brilliance. These inclusions are consistent with natural corundum — fine needles or pinpoint crystals — and in many cases act to soften specular reflection and enhance the velvety character often prized in Ceylon sapphires. The heat treatment applied here is a conventional thermal process used to improve color saturation and lessen the visibility of silk, and when properly executed it is stable and does not compromise the gem’s structural integrity.

On the Mohs hardness scale this sapphire registers a 9, placing corundum directly below diamond, which is a 10. This high hardness affords excellent resistance to abrasion and surface wear, making sapphire particularly well suited for everyday jewelry such as engagement rings, signet rings, and bracelets where contact with other materials is common. For practical comparison, topaz scores an 8, quartz a 7, and emeralds are typically reported in the 7.5 to 8 range but often display lower toughness due to natural fissures and cleavage, making corundum a more durable choice for daily wear than many colored stones. Corundum also benefits from favorable toughness characteristics and a lack of true cleavage, so while impactful blows to bezel walls or otherwise unsupported girdles should be avoided, routine wear in secure prong or bezel settings will maintain the stone’s integrity over decades. Because this sapphire has been heat treated and is not reported as fracture-filled, standard professional cleaning methods including ultrasonic and steam cleaners are generally acceptable, though we recommend periodic inspection of the mounting and avoidance of harsh chemical exposure. The Natural Sapphire Company provides guidance on ideal setting types to protect the girdle and shoulders and to showcase the mixed brilliant cut for maximum optical performance.