0.85 Ct. Blue Sapphire from Tanzania

This transparent 0.85 carat oval shape blue sapphire, with dimensions of 5.76 x 5.02 x 3.48 mm, is a specimen whose formation predates recorded history. Deep in the crust beneath what is now Tanzania, aluminum rich protoliths were subjected to regional metamorphism as tectonic plates converged and thickened. Under temperatures in excess of several hundred degrees Celsius and pressures sufficient to reorganize silicate lattices, aluminum and oxygen recombined to form corundum, the mineral family to which sapphire belongs. Trace concentrations of iron and titanium became incorporated into the corundum lattice during crystallization, and the intervalence charge transfer between iron and titanium produced the vivid blue that defines this stone. Over millions of years crystalline growth continued in pockets and veins, with slow cooling and minimal flux introduced by aqueous fluids, permitting well formed crystal faces to develop. Subsequent uplift and erosion liberated crystals into alluvial systems, and natural transport rounded external crystal features while preserving the internal crystalline order, until this particular crystal was recovered, ready for cutting.

The cutting and evaluation of this sapphire were executed with technical rigor to preserve both color and light performance. The cutter selected an oval outline to maximize face up color saturation in a stone of these dimensions, and employed a mixed brilliant cut, combining a brilliant style crown to enhance scintillation with a step influenced pavilion arrangement to deepen color and control light leakage. The resulting proportions produce a depth of three point forty eight millimeters, corresponding to an approximate depth ratio that enhances body color while maintaining lively return. Clarity was assessed at eye level and graded as very slightly included, indicating only minor internal features that do not detract from transparency or light transmission. Color is described as vivid in intensity, with a rich, saturated blue that exhibits pleochroic behavior, shifting subtly between deep blue and a slightly violet influenced blue when the stone is rotated. The polish is excellent, producing crisp facet junctions and mirror like facet planes that optimize brilliance and ensure that the color reads uniformly across the table. Importantly, this sapphire has undergone no enhancement, it is unheated and untreated, which preserves the natural trace element signature and the original crystal integrity.

From a connoisseurship perspective the gem offers a synthesis of geological pedigree, precise lapidary execution, and secure provenance. Origin is Tanzania, and the combination of vivid natural color, transparent body, and the mixed brilliant cut yields a stone that is adaptable to fine settings where color saturation is paramount. The oval shape provides versatility for ring, pendant, or bespoke designs, and the stone sits comfortably within popular size and proportion windows for elegant everyday wear. At The Natural Sapphire Company we document the gemological attributes for informed selection and for long term value retention, and our lapidaries emphasize facet symmetry and pavilion geometry to preserve weight while maximizing optical performance. For buyers who prioritize unenhanced material and geological authenticity, this sapphire represents a direct connection to deep time, its blue tone a record of elemental substitution within corundum, and its cut a modern translation of millions of years of earth processes into wearable form.