Gemstone
Diaspore
Diaspore (α-AlO(OH)) is the mineral species, first described by René Just Haüy in 1801. While diaspore is geologically common in bauxite ore worldwide, gem-quality color-change diaspore — the alexandrite-effect variety sold as Zultanite, Csarite, Ottomanite, and Turkizite — is documented only from a single locality: the İlbir Mountains of Türkiye. Buyer prices range from USD 750 per carat to USD 14,000+ per carat depending on weight band and color-change strength. This hub indexes every Zultpedia entry on the species.
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Gem Article
Zultanite Lab Reports — Why “No Treatment” Is the Documented Norm
A genuine Zultanite (color-change diaspore) laboratory report from GIA, IGS, or a recognized national lab will explicitly state "no evidence of treatment" in the treatment-disclosure section. This is the documented norm for…
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Gem Article
Zultanite — Fracture-Filling and Coating Detection in Gemological Labs
Fracture-filling and surface-coating treatments are not standard for Zultanite (color-change diaspore), but laboratories test for them as part of the standard identification protocol. FTIR spectroscopy detects organic resin fillers; surface inspection under…
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Gem Article
Zultanite Ring Settings — Bezel vs Prong Durability Trade-Offs
A bezel setting protects Zultanite (color-change diaspore) better than a prong setting because it surrounds the entire girdle with metal, distributing point impacts that could otherwise propagate the perfect {010} cleavage. Prong…
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Gem Article
Zultanite Resizing — Why Heat-Based Ring Sizing Threatens the Stone
Standard ring-resizing techniques use a torch flame to soften the metal shank. Zultanite (color-change diaspore) cannot tolerate the resulting thermal shock without significant cleavage risk because the {010} cleavage plane responds to…
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Property Guide
Crystal Habit of Diaspore — Tabular, Acicular, Massive
Diaspore commonly forms thin platy or tabular crystals flattened on {010}, occasionally elongated needle-like (acicular) crystals along the c-axis, and frequently as fine-grained massive aggregates within bauxite ore. Gem-quality crystals from the…
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Gem Article
Export Documentation for Türkiye-Sourced Zultanite
Türkiye-sourced color-change diaspore exported for the international gem trade typically carries documentation including a Türkiye Mineralogical Heritage attestation, customs declarations citing HS code 7103 (precious and semi-precious stones), and where applicable a…
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Property Guide
Optical Character of Zultanite — Biaxial Positive
Zultanite is biaxial positive: light traveling through the crystal splits into two rays with three principal refractive indices (nα 1.682–1.706, nβ 1.705–1.725, nγ 1.730–1.752), with nβ closer to nα than to nγ.…
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FAQ Cluster
Zultanite Jewelry Care — Frequently Asked Questions
Zultanite jewelry requires gentler handling than harder gems. Clean only with warm soapy water and a soft brush. Never use ultrasonic or steam cleaners. Store separately from harder gems. Avoid daily-wear ring…
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FAQ Cluster
How to Identify Real Zultanite — Frequently Asked Questions
Identifying genuine color-change diaspore requires five tests: color change between daylight and incandescent illuminants, trichroic pleochroism via dichroscope, refractive index 1.682–1.752 with strong birefringence, specific gravity 3.30–3.39, and a recognized laboratory report…
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FAQ Cluster
Zultanite vs Other Color-Change Gems — Frequently Asked Questions
Zultanite (color-change diaspore) is one of several color-change gems on the market, each distinguished by mineral species, hardness, source region, and the strength and direction of color shift. Alexandrite (chrysoberyl) is the…