Tanzanite 80.59 ct – Octagonal Cut, Calibrated, Natural, Lab Certified

Natural Tanzanite 80.59 ct – Octagonal Calibrated Blue Gemstone from Tanzania

Tanzanite 80.59 ct – Octagonal Cut, Calibrated, Natural, Lab Certified

Name: Tanzanite 80.59 ct – Octagonal Cut, Calibrated, Natural, Lab Certified
Brand: SOSNA Gems
Availability: InStock

Price on request

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Gemstone Specification

Carat Weight 80.59

Dimensions 23.09 x 23.09 x 16.40 mm

Color Blue

Clarity Eye Clean

Shape Octagonal

Treatment Heated

Origin Tanzania

Certification IGI

This 80.59 ct Tanzanite features a precise 23 mm calibrated octagonal cut, maximizing brilliance and symmetry. The gem’s intense blue saturation reflects its Tanzanian origin, further enhanced by standard heat treatment. With excellent clarity, balanced proportions, and certified authenticity, this Tanzanite is ideal for high-end jewelry settings or as a secure, appreciating hard asset. The rare octagonal shape offers visual distinction and added collector value.

Tanzanite 80.59 ct – Octagonal Cut, Calibrated, Natural, Lab CertifiedPrice on request

From gemstone to jewelry

This gemstone can be transformed into a custom-made jewel.
The example shown illustrates how a loose stone may be set into a bespoke design.
Each final piece is created individually in consultation with our experts.

Loose gemstone

Bespoke jewelry

Custom jewelry service

Selected gemstones from our collection can be transformed into bespoke jewelry.
The example above illustrates one of many possible design outcomes, each created individually in consultation with our experts to reflect both your preferences and the stone’s natural character.

Learn more about custom jewelry

Insured Express Delivery

Fully insured worldwide shipping with discreet packaging.

Gemological Disclosure

Each gemstone is professionally examined and accompanied by clear gemological information regarding its characteristics, treatments, and origin.

Ethical & Transparent Sourcing

We guarantee legal and ethical origin of every gemstone.

Secure & Trusted Purchase

Protected payments, professional handling, and client confidentiality.

Gemological overview

Technical and gemological information about this gemstone variety.

Gemological profile

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.

Durability & suitability

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.

Treatments & authenticity

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.

Our approach to gemstones

We focus primarily on natural, untreated gemstones, valued for their authenticity and inherent beauty.
Any treatments or enhancements are always clearly disclosed, allowing our clients to make informed decisions based on transparent gemological standards.

Sosna Gems is not a licensed financial advisor. Gemstones are collectibles, not securities. Past performance is not indicative of future results. Legal & risk disclosure .