Topic
Lapidary
Lapidary entries on Zultpedia cover the cutting and polishing of color-change diaspore: the perfect cleavage on {010} that causes ~97% rough loss, master-cutter conventions for orienting the table to maximize color-change visibility while minimizing cleavage exposure, and the cut-grade evaluation rubric specific to Zultanite.
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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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Glossary Term
Cabochon
A polished but non-faceted dome-shape cut, typically used for opaque or asterism-bearing stones. Color-change diaspore is rarely cut as cabochon because the alexandrite effect is most visible through facet returns. Cabochon-cut diaspore…
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Glossary Term
Facet
A flat polished surface on a cut gemstone, geometrically arranged to maximize light return and color display. Color-change diaspore is typically faceted in oval, cushion, pear, or emerald cuts oriented so the…
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Glossary Term
Table
The large flat top facet of a cut gemstone, oriented perpendicular to the optic axis in most faceted stones. For color-change diaspore, the cutter orients the table so that the table-up viewing…
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Glossary Term
Pavilion
The lower portion of a faceted gemstone, below the girdle. Pavilion facets reflect light back through the table to produce brilliance. Diaspore's strong birefringence (~0.048) makes pavilion facet edges visibly doubled when…
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Glossary Term
Girdle
The narrow band that forms the widest perimeter of a faceted gemstone, separating the crown (top) from the pavilion (bottom). The girdle is where most jewelry settings grip the stone. For diaspore,…
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Glossary Term
Crown
The upper portion of a faceted gemstone, above the girdle and including the table facet. Crown angles affect light return and the visibility of the gem's color through the table. For diaspore,…
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Glossary Term
Culet
The pointed bottom tip of a faceted gemstone, where the pavilion facets meet. A pointed culet is structurally vulnerable; many modern cuts use a small flat "open culet" or rounded keel instead.…
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Gem Article
Why Zultanite Is Rare — Single Source, Cleavage Loss, and Trace Chemistry
Zultanite's rarity has three structural causes: (1) single-source origin — gem-quality color-change diaspore comes from one mountain range in Türkiye, with no comparable secondary locality in commercial production; (2) lapidary loss —…