1.64 Ct. Blue Sapphire from Tanzania

This cushion shape blue sapphire presented by The Natural Sapphire Company is a finely proportioned, transparent gemstone weighing 1.64 carats, with precise measurements of 7.73 by 6.82 by 3.28 millimeters. The cutting style is faceted, executed as a mixed brilliant cut that combines a brilliant faceted crown with pavilion facet architecture tuned for corundum. The combination of an expertly weighted table and a slightly shallower pavilion relative to the average length and width yields a depth ratio of approximately forty five percent, producing an excellent face up spread that makes the gem read larger than its carat weight would suggest. Clarity is graded as slightly included when evaluated at eye level, with minor internal features that do not significantly interrupt transparency, and the polish is graded excellent, giving the facet junctions razor sharp edges and mirror like facet surfaces. Importantly this sapphire is untreated, showing no enhancement, and its provenance is Tanzania, which contributes to the stone s natural zonal and crystal growth characteristics that are consistent with East African corundum.

From an optical and gemological perspective this sapphire s brilliance and visual performance are defined by three interacting factors, facet geometry, refractive properties of corundum, and intense color saturation. Corundum has a refractive index around one point seven six to one point seven seven, and a relatively low dispersion, therefore the visual brilliance is not driven by spectral fire in the way that diamonds exhibit, but by concentrated light return and contrast scintillation across the pavilion and crown facets. The mixed brilliant cut used here maximizes that light return by arranging small, polished crown facets to break white light into dynamic flashes, while the pavilion facet angles are optimized to reflect light back through the table and crown. The result is lively scintillation and crisp light flashes that appear as vibrant blue highlights, rather than the colorless white brilliance of higher dispersion gems. Compared to commonly available blue gemstones such as blue topaz and aquamarine, which are typically paler and have lower pleochroic behavior, this sapphire maintains intense color intensity under varied lighting, producing a saturated cornflower to royal blue face up that reads deeply even when viewed from oblique angles. Against diamond, the visual experience differs, diamonds offer higher brilliance and fire because of their dispersion and higher refractive index, however diamonds are colorless by design, and they do not present the same depth of hue that a strongly saturated sapphire like this one provides. The sapphire s pleochroism is an additional advantage, delivering subtle shifts between deeper and lighter blue tones as the gem is tilted, adding perceived depth and liveliness that common pale blue gems cannot replicate.

For the discerning buyer who evaluates craftsmanship and setting compatibility alongside optical performance, this Tanzanian cushion sapphire offers clear advantages. The mixed brilliant faceting pattern provides an attractive balance between large, clean flashes and finely speckled scintillation, making it ideal for settings that emphasize the table view, such as three stone rings with accent diamonds, or halo designs where the intense saturated color provides a striking contrast to white metals. The slightly included clarity grade is typical for natural, untreated corundum and often allows for confident setting without the need for protective bezels, while the excellent polish contributes to easy mounting and excellent face up performance under both natural and artificial lighting. The untreated origin from Tanzania is noteworthy for collectors and connoisseurs, because it assures that the color and crystal growth features are entirely natural, which has a direct impact on rarity and long term value.

In summary, this one point six four carat cushion shape blue sapphire from The Natural Sapphire Company combines technical precision in cutting, excellent surface finish, and a naturally intense color intensity to achieve a type of brilliance that is different from but equally compelling as the brilliance found in more common gemstones. Its mixed brilliant architecture and optimized proportions deliver superior face up spread and lively scintillation, its corundum optical properties and pleochroic depth create rich color dynamics, and its untreated Tanzanian origin affirms authenticity and scarcity. For customers seeking a gemstone with technical excellence, measured light performance, and natural, uncompromised color, this sapphire is an especially strong candidate, and our team at The Natural Sapphire Company can provide detailed facet maps, additional photos under multiple lighting conditions, and setting recommendations to assist in final selection.