Tanzanite 166.88 ct – Blue, Cushion Cut, Natural, Lab Certified

Tanzanite is a blue to violet-blue variety of the mineral zoisite, valued for its rich coloration and distinct pleochroism, which can display different hues depending on viewing angle and lighting conditions. In gem-quality material, tanzanite is appreciated for its depth of color and refined visual character, particularly in well-cut stones.
Chemically composed of calcium aluminum silicate (Ca₂Al₃(SiO₄)₃(OH)), tanzanite crystallizes in the orthorhombic crystal system and belongs to the silicate mineral group. Transparent gem-quality specimens typically display a vitreous luster with good clarity.
The refractive index of tanzanite generally ranges from approximately 1.69 to 1.70, contributing to a balanced brilliance rather than intense sparkle. Tanzanite is found exclusively in a single geographic area near Mount Kilimanjaro in Tanzania, a factor that contributes to its distinct identity among colored gemstones.

With a hardness of approximately 6 to 6.5 on the Mohs scale, tanzanite offers moderate durability suitable for jewelry when properly set and worn with care. While it can be used in a range of designs, it performs best in pieces that are less exposed to frequent impact, such as pendants, earrings, and protected ring settings.
Due to its moderate hardness and cleavage, thoughtful setting design is particularly important, especially for rings intended for regular wear. Tanzanite’s combination of color depth and elegance makes it especially well suited for refined, occasional-wear jewelry and expressive statement designs.

Tanzanite is commonly heat treated to enhance its blue and violet coloration, a practice that is standard within the gem trade and considered permanent and stable when properly disclosed. This treatment does not compromise the structural integrity of the gemstone.
Any treatments or enhancements are always clearly stated for each individual gemstone. Every stone is professionally examined, and transparent disclosure is regarded as a fundamental part of responsible gemological practice, allowing clients to make informed and confident decisions.