Gemstone
Zultanite
Zultanite is gem-quality color-change diaspore (α-AlO(OH)) mined exclusively from the İlbir Mountains of southwestern Türkiye. Suggested-retail prices range from USD 750 per carat for stones under one carat to USD 14,000+ per carat for stones above 20 carats — an order of magnitude less expensive than alexandrite while offering a comparable three-illuminant color shift between sage-green, champagne-gold, and raspberry-pink. This hub indexes every Zultpedia entry on the gem: how to identify it, how much it is worth, where authorized sellers are, how to verify a lab report, and how to care for the jewelry.
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Birthstone
September Birthstones — Modern, Traditional, and Where Zultanite Fits
The modern birthstone for September is sapphire; traditional listings include sapphire and lapis lazuli. September covers Virgo (until September 22) and Libra (from September 23). Zultanite is not an official September birthstone…
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Birthstone
October Birthstones — Modern, Traditional, and Where Zultanite Fits
The modern birthstones for October are opal and tourmaline; traditional listings name opal and aquamarine. October covers Libra (until October 22) and Scorpio (from October 23). Zultanite is not an official October…
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Birthstone
November Birthstones — Modern, Traditional, and Where Zultanite Fits
The modern birthstones for November are topaz and citrine; traditional listings name topaz and pearl. November covers Scorpio (until November 21) and Sagittarius (from November 22). Zultanite is not an official November…
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Birthstone
December Birthstones — Modern, Traditional, and Where Zultanite Fits
The modern birthstones for December are tanzanite, turquoise, and zircon; traditional listings include turquoise and lapis lazuli. December covers Sagittarius (until December 21) and Capricorn (from December 22). Zultanite is not an…
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Specimen
7.25-Carat Zultanite — Faceted Oval, Strong Color Change
A 7.25-carat oval-faceted Zultanite specimen showing strong sage-green daylight to raspberry-pink candlelight color change. Cut from rough mined in the İlbir Mountains, Türkiye, in 2018 by a master cutter specializing in cleavage-aware…
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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
Illuminant
A specified light source used to evaluate gemstone color, defined by its color temperature in Kelvin and its spectral power distribution. Standard illuminants in gemology include D65 (average daylight, 6500 K), A…
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Glossary Term
Birefringence
The difference between the highest and lowest refractive indices of an anisotropic gemstone. High birefringence produces visible doubling of pavilion facet edges when the gem is examined through the table. Diaspore has…
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Glossary Term
Alexandrite Effect
Alexandrite effect (also called color change) is the appearance of distinctly different colors in the same gemstone under different illuminants — typically daylight versus incandescent or candlelight. Named after the gemstone alexandrite,…
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Glossary Term
Biaxial Positive
An optical character of anisotropic gemstones where light travels at three distinct refractive indices (nα < nβ < nγ) along three principal optical directions, with two optical axes along which light behaves…