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Gemstone Encyclopedia
Chrome Diopside: Why Cleavage and Fracture Matt...
Chrome diopside durability depends on two good cleavages at near-right angles, possible parting, and brittle fracture, not on Mohs hardness alone.
Chrome Diopside: Why Cleavage and Fracture Matt...
Chrome diopside durability depends on two good cleavages at near-right angles, possible parting, and brittle fracture, not on Mohs hardness alone.
Crystal Opal and Its Lookalikes: Reading Refrac...
Crystal opal is isotropic with no birefringence and a refractive index near 1.45. Learn how optical character and RI distinguish it from glass, quartz, beryl, and synthetic opal lookalikes.
Crystal Opal and Its Lookalikes: Reading Refrac...
Crystal opal is isotropic with no birefringence and a refractive index near 1.45. Learn how optical character and RI distinguish it from glass, quartz, beryl, and synthetic opal lookalikes.
Reading Tahitian Pearls Without Reading Their O...
Tahitian pearl appearance reflects nacre structure and pigments, not geological origin. Learn why color cannot prove natural status, treatment, or specific island source.
Reading Tahitian Pearls Without Reading Their O...
Tahitian pearl appearance reflects nacre structure and pigments, not geological origin. Learn why color cannot prove natural status, treatment, or specific island source.
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.