5.90 Ct. Chrome Tourmaline from Tanzania

This chrome tourmaline from Tanzania offered by The Natural Gemstone Company is a study in precision cutting and pure, natural color. The stone weighs 5.90 carats, and presents an oval outline with dimensions of 13.64 by 10.76 by 6.41 millimeters. The cutter chose a mixed brilliant style, combining a brilliant facet arrangement on the crown with carefully proportioned pavilion facets, to optimize both face up presence and internal light performance. Clarity is graded as eye clean when examined at normal viewing distances, and the surface finish is described as excellent polish, a level of workmanship that maximizes scintillation and contrast. There has been no enhancement to this material, and the vivid green saturation is a primary characteristic of chromium rich tourmaline from the known deposits of Tanzania.

The mixed brilliant faceting on this oval has been executed to emphasize strong return of white light and colored flashes, while maintaining a broad, saturated face up color. The crown displays modified brilliant facets that break the table window into a lively pattern of small to medium sized facets, yielding crisp scintillation when the stone moves under direct light. The pavilion facets are tailored to the natural optic orientation of the rough, producing effective light trapping and return, and minimizing dark areas that can occur in shallow cuts. Based on the measured dimensions the stone exhibits a depth of approximately 52.5 percent relative to the average girdle diameter, a proportion that increases apparent size on the finger while retaining robust brilliance due to the controlled pavilion angles and precise symmetry. The overall symmetry and facet junctions are tight, and the excellent polish contributes to maximum contrast and life in the gem, attributes that are immediately evident in natural daylight and in artificial illumination used for gem appraisal.

Optically this chrome tourmaline shows the hallmark qualities of chromium coloration and tourmaline birefringence, results that will interest technical buyers and collectors. The vivid green hue originates from chromium substituting into the elbaite crystal structure, producing chromatic saturation that is deep and evenly distributed across the pavilion and crown. Tourmaline is a biaxial mineral with refractive index values that typically fall in the approximate range of 1.624 to 1.644 depending on composition, and with birefringence in the approximate range of 0.014 to 0.020, factors that contribute to the pronounced internal color zoning and pleochroism seen in many specimens. This stone demonstrates directional color response, with slightly different tones visible as the stone is rotated, a behavior that cutters can exploit when orienting the table for the most attractive face up color. Physical durability is robust for everyday wear, with a Mohs hardness around 7.0 to 7.5 and a specific gravity near 3.06, properties that make this tourmaline well suited to fine jewelry settings provided standard care practices are followed.

As a centerpiece in a collection this 5.90 carat green chrome tourmaline stands out for its combination of weight, vivid natural color, and masterful cutting. The absence of enhancement assures collectors and connoisseurs that the rich green is wholly natural, and the Tanzanian origin provides an additional provenance narrative that many buyers appreciate. The mixed brilliant cut lends itself to a variety of mounting styles, from solitary rings that showcase the oval outline to bespoke pendants that allow a larger viewing window under soft lighting. To preserve the polish and maintain optical performance we recommend routine gentle cleaning with warm soapy water and a soft brush, avoiding ultrasonic cleaning if the pendant or ring introduces stresses from mounting, and avoiding prolonged exposure to heat. The Natural Gemstone Company stands behind the documented attributes of this stone, and our gem specialists can advise on setting orientations that best display the pleochroic tendencies for maximum visual impact, ensuring that when this tourmaline is placed under spotlight or daylight it will perform as the luminous, eye catching centerpiece it was cut to be.