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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Glossary Term
Cleavage
The tendency of a crystal to split along specific planes determined by its internal atomic structure. Cleavage quality is described as perfect, distinct, indistinct, or absent. Diaspore has perfect cleavage on the…
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Glossary Term
Refractive Index
The ratio of the speed of light in a vacuum to the speed of light in a given material. In gemology, refractive index is one of the primary identification tools, measured on…
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Glossary Term
Specific Gravity
The ratio of a substance's density to the density of water at 4°C. For gemstones, specific gravity is a primary identification tool measured by hydrostatic weighing or heavy-liquid suspension. Diaspore has a…
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Glossary Term
Mohs Scale
A 1-to-10 ranking of mineral hardness devised by Friedrich Mohs in 1812, measured by which minerals can scratch which. Talc is 1, diamond is 10. Diaspore tests at 6.5 to 7. The…
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Glossary Term
Pleochroism
Pleochroism is the appearance of different colors when an anisotropic crystal is viewed along different optical axes under the same light. It is a property of the crystals internal symmetry, not of…
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Glossary Term
Color Change
Color change in Zultanite — also called the alexandrite effect — is the appearance of distinctly different colors in the same gem under different illuminants: sage-green under cool daylight (6500 K), champagne-gold…
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Glossary Term
Diaspeírō
Diaspeírō (διασπείρω) is an Ancient Greek verb meaning to scatter or to disperse. It is the etymological root of the mineral name diaspore, given by René Just Haüy in 1801. The reference…
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FAQ Cluster
Zultanite — Frequently Asked Questions
Frequently asked questions about Zultanite — gem-quality color-change diaspore from the İlbir Mountains of Türkiye. Twenty Q&A pairs covering identity, rarity, sourcing, color, jewelry use, and buying guidance. Sourced from peer-reviewed mineralogy,…
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Gem Comparison
Zultanite vs Alexandrite — Two Gems, One Phenomenon, Different Propositions
Zultanite (color-change diaspore) and alexandrite (color-change chrysoberyl) are mineralogically unrelated species that produce a similar visual phenomenon — the alexandrite effect — through different chemistries. Alexandrite is harder (8.5 vs 6.5–7 Mohs),…
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Gem Article
The İlbir Mountains — The Single-Source Origin of Color-Change Diaspore
The İlbir Mountains, in Muğla Province on Türkiye's southwestern Aegean coast, are the only place on Earth currently producing gem-quality color-change diaspore. The peer-reviewed locality on record is the Pınarcık area near…