5.40 Ct. Spinel from Tanzania

This item from The Natural Gemstone Company is a beautifully transparent blue spinel weighing 5.40 carats, presented in a classic round shape with precise dimensions of 10.56 x 10.54 x 7.23 millimeters. The gem is cut to a mixed brilliant configuration, with an excellent polish and a clarity grade assessed as very slightly included when viewed at eye level. Color intensity is vivid and even across the table, and the stone is completely natural with no enhancements. The origin is Tanzania, a source known for producing a spectrum of high quality spinels, and the combination of weight, transparency and vivid blue color places this piece within a select tier of collectible spinel material suitable for both connoisseurs and designers seeking a striking center stone.

From a gemological perspective, the mixed brilliant cut used on this round spinel is deliberately chosen to balance light performance and color saturation for a stone with a moderate refractive index and low dispersion. Spinel typically exhibits a refractive index in the range of about 1.712 to 1.718 and a relatively low dispersion, characteristics that favor well proportioned facet geometry for optimal light return. The mixed brilliant style pairs a brilliant facet arrangement on the crown with a modified pavilion design that controls the path of incoming light to maximize bright return and scintillation while minimizing windowing. The specific proportions of this stone, with a depth of 7.23 millimeters against an average diameter of about 10.55 millimeters, produce an overall depth of approximately 68.5 percent, which enhances face up color saturation and yields a deep vivid blue without becoming overly dark. The excellent polish on each facet reduces surface scattering, allowing the internal facet junctions to act efficiently as mirrors, and the result is a lively balance of body color and pinpoint flashes that will read as vivid blue in most lighting environments.

Clarity and natural origin contribute substantially to the gemological and market value of this spinel, and it is important to understand how the very slightly included grade affects performance and longevity. The very slight inclusions observed at eye level are minimal, do not interfere with transparency, and do not compromise the structural integrity of the stone. Because spinel is isometric and lacks directional cleavage, it is well suited to everyday jewelry settings, and the absence of thermal or fracture filling treatments preserves long term value and collector appeal. Tanzanian provenance adds provenance value for informed buyers, as Tanzanian occurrences are known for producing intensely colored and well crystallized spinels, and documented origin supports accurate valuation and resale potential. For buyers who prioritize natural material and clarity, this stone represents a rare alignment of meaningful carat weight, optical quality, and untreated origin.

For the educated buyer or designer, this blue spinel offers practical advantages and aesthetic versatility. At 5.40 carats and a round mixed brilliant cut, it is an excellent candidate for a substantial solitaire ring, a dramatic pendant, or a bespoke piece that allows the stone to be set face up to maximize light play. The mixed brilliant cutting style ensures that the gem will retain lively scintillation during movement, while the deliberate depth enhances color intensity when set. The combination of vivid color, very slight inclusions, excellent polish, and natural Tanzanian origin makes this stone a sound investment grade choice from The Natural Gemstone Company. We recommend mounting that preserves the crown and pavilion symmetry, and a professional setting that allows light to enter the table unobstructed will best showcase the stone's carefully engineered balance of brilliance and saturated blue color.