5.42 Ct. Blue Sapphire from Thailand

This oval, transparent blue sapphire presents a substantial and well balanced 5.42 carat weight, making it a statement quality gem for discerning buyers who prioritize both size and technical excellence. The measured dimensions of 11.85 millimeters by 9.56 millimeters with a pavilion depth of 5.13 millimeters produce a depth that is approximately 48 percent of the average girdle diameter, a proportion that promotes strong light return while retaining the broad face up appearance desirable in classic oval proportions. The mixed brilliant cut has been executed to marry the scintillation of brilliant faceting with the controlled light performance of modified pavilion geometry, yielding a lively interplay between pinpoint sparkle and large facet flashes. Facet junctions are sharp and meet with precise symmetry, and the excellent polish across crown and pavilion surfaces enhances specular reflection, which contributes directly to perceived brightness and luster. The oval outline shows gentle curvature and uniform symmetry along the length and width axes, which supports predictable setting orientation in ring, pendant, and bespoke designs.

Color characteristics are central to this sapphires premium appeal, the stone exhibiting vivid color intensity with a saturated pure blue hue and a slight velvety overtones that add visual depth without sacrificing saturation clarity interplay. The vivid intensity indicates a robust combination of medium to medium dark tone with strong saturation, producing the deep blue that is highly sought after in high end sapphires. Origin is Thailand, a source known for sapphires that often show richer, deeper blue tones, and the documented enhancement by heat treatment is a stable, industry accepted process that has been applied to optimize both color uniformity and to reduce microscopic silk that can affect transparency. The clarity grade is assessed as very slightly included at eye level, indicating minor internal features that do not materially detract from overall transparency or durability. Under loupe examination small silk traces or pinpoint inclusions are expected, but they remain subordinate to the dominant optical qualities, allowing the stone to read clean to the unaided eye when mounted. The combination of high clarity, vivid chroma, and excellent polish yields exceptional presence when viewed face up.

From a valuation and design perspective the 5.42 carat weight itself elevates this sapphire into a premium market tier, because crystals of this size with vivid color and pleasing proportions are comparatively rare. The carat weight not only increases intrinsic value, it transforms the stone into a central design element that can stand alone as a solitary feature in a classic four or six prong head, or serve as the focal point in a halo or three stone composition where the dimensional spread and visual dominance are desired. For settings that maximize brilliance, a well spaced prong architecture that permits light entry to the pavilion is recommended, while bezel designs may be preferred when additional protection is required for active wearers. As custodians of provenance and craftsmanship, The Natural Sapphire Company certifies the documented origin and the heat treatment status, and we can advise on mounting options that preserve the stones optical performance and mechanical safety. Routine care is straightforward, cleaning with warm soapy water and a soft brush, avoiding harsh chemicals and ultrasonic cleaning only when the mounting and treatment history are confirmed compatible. This sapphire is an excellent candidate for bespoke commissions, offering the technical attributes and dimensional presence that knowledgeable buyers seek, a rare combination of vivid color, precise mixed brilliant faceting, very slightly included clarity, and a sizeable 5.42 carat weight that together define premium quality.