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Gemstone Encyclopedia
Selenite Color Zoning and the Case for Cabochon...
Why is selenite often cut as cabochons? Learn how gypsum's color zoning, cleavage, softness, and fibrous structure make cabochon cutting the better optical and structural choice.
Selenite Color Zoning and the Case for Cabochon...
Why is selenite often cut as cabochons? Learn how gypsum's color zoning, cleavage, softness, and fibrous structure make cabochon cutting the better optical and structural choice.
Mahogany Obsidian: Why Cut Orientation Controls...
Mahogany obsidian is a natural volcanic glass. Learn why cut orientation, dome height, and surface finish determine whether its brown-and-black banding reads clearly or looks flat.
Mahogany Obsidian: Why Cut Orientation Controls...
Mahogany obsidian is a natural volcanic glass. Learn why cut orientation, dome height, and surface finish determine whether its brown-and-black banding reads clearly or looks flat.
Reading Sapphire Inclusions Against the Crystal...
Learn how sapphire crystal orientation affects visible growth zoning, inclusions, pleochroism, and identification, and why the same stone can look different from different directions.
Reading Sapphire Inclusions Against the Crystal...
Learn how sapphire crystal orientation affects visible growth zoning, inclusions, pleochroism, and identification, and why the same stone can look different from different directions.
Taaffeite and the Iridescence Problem: Why the ...
Taaffeite is a rare beryllium-bearing mineral, not a classic iridescent gem. Learn why taaffeite is not defined by play of color or interference effects, how pleochroism differs from iridescence, and...
Taaffeite and the Iridescence Problem: Why the ...
Taaffeite is a rare beryllium-bearing mineral, not a classic iridescent gem. Learn why taaffeite is not defined by play of color or interference effects, how pleochroism differs from iridescence, and...
Why Natural Pearls Vary in Color: Nacre Structu...
Natural pearl color comes from organic pigments in nacre, layered aragonite structure, and environment. Learn how body color, overtone, and orient differ and why appearance alone cannot prove origin.
Why Natural Pearls Vary in Color: Nacre Structu...
Natural pearl color comes from organic pigments in nacre, layered aragonite structure, and environment. Learn how body color, overtone, and orient differ and why appearance alone cannot prove origin.
Why Alexandrite Changes Color: The Optics and T...
Alexandrite's color change explained by chromium absorption and light spectrum. Learn why some stones show strong green-to-red shifts and how to distinguish natural from synthetic.
Why Alexandrite Changes Color: The Optics and T...
Alexandrite's color change explained by chromium absorption and light spectrum. Learn why some stones show strong green-to-red shifts and how to distinguish natural from synthetic.