1.76 Ct. Spinel from Ceylon (Sri Lanka)

This blue spinel began its geological story millions of years ago deep within a carbonate platform that later became the high grade metamorphic terrain of Ceylon Sri Lanka. In that ancient environment layers of sediment rich in aluminum and magnesium were subjected to protracted burial, thermal gradients and the mechanical forces associated with tectonic convergence. Intrusive pulses and regional metamorphism provided heat and fluid phases that mobilized chemical components, enabling the crystallization of spinel with the stoichiometry MgAl2O4. Under high temperature and pressure conditions small nuclei coalesced and grew into euhedral crystals within a calc silicate and marble matrix, occasionally incorporating trace transition metals that later produced the intense blue coloration. Over geologic time, uplift and erosion liberated these spinel crystals from their primary host, and successive cycles of weathering and fluvial transport concentrated the harder, chemically inert spinel into placer deposits. It is from these alluvial gravels and residual pockets that Sri Lanka has yielded many of the most desirable transparent spinels, and the crystal you see retained the pristine growth characteristics imparted by that deep time history.

The specimen offered by The Natural Gemstone Company is a transparent cushion shaped blue spinel, weighing 1.76 carat, with finished dimensions of 7.15 by 6.22 by 4.54 mm, executed in a mixed brilliant cut that combines a faceted crown designed for dispersion with a pavilion architecture optimized for color return. The clarity grade is very very slightly included as evaluated at eye level, a grade which indicates that inclusions are minute and do not compromise the apparent transparency or light transmission under normal viewing. Color is classified as intense, a saturation level that demonstrates strong absorption in the visible blue region typically produced by trace iron and in some cases cobalt, and the polish is excellent reflecting meticulous lapidary finishing. No enhancement has been applied to this stone, the material is natural and untreated, and the documented origin is Ceylon Sri Lanka. For the technical buyer these parameters matter, because the combination of a concentrated, natural color, VVS clarity at loupe and eye inspection, and an unenhanced state make this an exemplar of high quality spinel suitable for both scientific collection and fine jewelry application.

From a gemological and cutting perspective the choice of a mixed brilliant cut on a cushion outline reflects a deliberate strategy to balance color saturation with lively optical performance. Spinel is singly refractive and isotropic, with an index of refraction in the neighborhood of 1.718, and it exhibits no pleochroism, so the cutter can rely on symmetric pavilion geometry and crown facet arrays to control scintillation and light return without compensating for directional color effects. The mixed brilliant approach typically employs a brilliant style crown to maximize small facet reflections and fire, while the pavilion uses a variant of angular, step influenced facets or reduced pavilion facets to increase the path length of light through the material and thereby deepen the perceived color. For this 7.15 by 6.22 by 4.54 mm cushion the lapidary calibrated the table diameter and crown height to avoid windowing, maintained proportional pavilion depth to prevent the stone from appearing too shallow or grassy, and preserved a fine girdle thickness to allow secure setting without excessive loss of material. The excellent polish you observe is the result of controlled successive grits and final high luster laps that remove residual facet abrasions, enhancing transparency and enabling crisp reflection boundaries from each facet plane.

The craftsmanship and inherent material properties together define how this spinel will behave in wearable contexts and in comparative evaluation. With a Mohs hardness near 8 and a specific gravity around 3.6, spinel is both durable and dense enough to sit securely in a variety of mountings, and the cushion shape with its softened corners facilitates both bezel and multi prong settings. The intense blue of this Ceylon spinel can be presented either as a solitary center stone or amplified with halo accents, and the mixed brilliant cut will display a combination of vivid color and scintillating facet play under direct and diffused lighting. Because this gem is untreated, any future buyer can be assured that its color stability is intrinsic rather than the result of diffusion or other laboratory modification. At The Natural Gemstone Company we document provenance and treatment status for each parcel, and we are prepared to provide high resolution images and microscope photography on request to illustrate the very very slightly included clarity characteristics, facet junction precision, and the excellent polish finish. If you require gemological reports or custom setting recommendations that respect the cutting geometry and optical orientation, our team can advise on mounting angles and prong placement to preserve light return and minimize risk to the girdle during setting.