13.71 Ct. Cabochon Tanzanite from Tanzania

This 13.71 carat round violet tanzanite from Tanzania, offered by The Natural Gemstone Company, presents a carefully executed cabochon form with dimensions of 13.02 by 13.02 by 9.59 millimeters, and a domed profile that maximizes the stone s translucency and intense color intensity. Cut as a classical high dome cabochon rather than faceted, the piece relies on precise symmetry and a well balanced dome height to showcase tanzanite s strong pleochroism so that blue and violet wavelengths are integrated into a visually saturated violet face up. Clarity is graded included at eye level, with internal features consistent with natural zoisite such as feathering and healed fissures that are typical and compatible with cabochon cutting, and these inclusions interact with light to create zones of depth rather than detract from the visual appeal. The polish is excellent, exhibiting a bright vitreous luster across the dome, and the finishing process uses progressive abrasives and final oxide polishing to achieve a smooth mirror surface that enhances light transmission. The stone has been heat treated to stabilize and intensify the violet hue, a standard and permanent enhancement for tanzanite that converts brownish zoning to the desired blue violet range.

From a durability and practical use perspective this tanzanite registers approximately 6.5 to 7.0 on the Mohs scale, which positions it well below corundum and diamond, and close to quartz in hardness, therefore caution in daily wear is advised when compared with sapphire at 9 and diamond at 10. The stone s specific gravity near 3.35 and refractive index in the vicinity of 1.69 to 1.70 contribute to substantial face up color and a stable body tone, however the moderate hardness means that protective settings such as bezels or halo mounted styles are recommended for rings, while pendants and earrings offer lower risk of abrasion. Ultrasonic cleaning is not recommended where there are visible internal fractures, steam cleaning should be avoided, and routine cleaning with warm soapy water and a soft brush will preserve the excellent polish. The heat treatment is stable under normal wearing conditions, and the combination of the substantial cabochon thickness, the intense natural violet color, and the considered cutting and polishing approach make this specimen an attractive choice for collectors and settings that value color intensity and tactile presence.