Natural tanzanite, 9.86 carats, purplish-blue color, round cut, heat-treated, rare investment gemstone

Natural Tanzanite 9.86 ct – Round Cut, Purplish Blue

Name: Natural Tanzanite 9.86 ct – Round Cut, Purplish Blue
Brand: SOSNA Gems & Jewellery
SKU: 2885448
Price: 187840.00 CZK
Availability: InStock

187.840,00 CZK

Gemstone Specification

Carat Weight 9.86

Dimensions 12.94 x 12.94 x 9.65 mm

Color Purplish Blue

Clarity Eye Clean

Shape Round

Treatment Heated

Origin Tanzania

Certification GIA

This 9.86 carat natural tanzanite presents a vivid purplish-blue color, enhanced by standard heat treatment, which is customary for this gemstone. Measuring 12.94 x 12.94 x 9.65 mm, it is expertly faceted into a round cut — a shape that is rare in larger tanzanites due to the high weight loss during cutting. With its combination of size, clarity, and balanced proportions, this gemstone holds strong appeal for serious collectors and strategic investors. It may be treasured as a long-term asset or selected as the focal point for an exceptional custom jewelry design.

Natural Tanzanite 9.86 ct – Round Cut, Purplish Blue

187.840,00 CZK

From gemstone to jewelry

This example illustrates one possible way a gemstone may be developed into a bespoke piece. Final design is always defined individually, based on the stone and its natural character.

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Bespoke jewelry

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Each design is developed individually, guided by the stone, its proportions and natural character.

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Gemological Disclosure

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

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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 .