Physical and Optical Properties of Gemstones


Learn about gemstone color, crystallography, hardness, chemical makeup and more.

Jade Toughness and Care

Jade Toughness and Care

Jade toughness is legendary. However, this gem isn’t indestructible. Learn what makes jadeite and nephrite so tough and how to...
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Gemstone Optics: The Basics

Gemstone Optics: The Basics

Accurately measuring optical properties is critical for identifying gemstones. This article covers the basic terminology and concepts of gemstone optics....
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Gemstone Optical Properties

Gemstone Optical Properties

Learn how gemstone optical properties, like refractive index and pleochroism, help gemologists identify gems and lapidaries choose cuts.
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What is Gemstone Cleavage?

What is Gemstone Cleavage?

Gemstone cleavage is a break in a crystal along internal planes. Learn the science behind this and the difference between...
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Descriptive Crystallography for Gemologists

Descriptive Crystallography for Gemologists

Crystallography is the study of crystalline solids. Learn the most common terms gemologists use to describe the structure of crystal...
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Gemstone Color Measurements and Specifications

Gemstone Color Measurements and Specifications

Gemstone color measurements are hard to make with conventional color-order systems. Learn how recent colorimetry tech advances have improved accuracy....
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Gemstone Color Change Phenomena

Gemstone Color Change Phenomena

Why do certain gems change color under different lights? Explore gemstone color change phenomena and the difference between natural and...
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What are Allochromatic and Idiochromatic Gems?

What are Allochromatic and Idiochromatic Gems?

Learn the difference between allochromatic and idiochromatic gems and why some gem species can occur in many color varieties and...
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Phenomenal Gems: Cat's Eyes, Star Stones, and More

Phenomenal Gems: Cat's Eyes, Star Stones, and More

Phenomenal gems seem to do magical things with light. Learn the science behind optical effects like cat’s eyes and star...
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Gemstone Physical Properties

Gemstone Physical Properties

The optical properties of gems attract our eyes and can give a cut stone a unique character. However, gemstone physical...
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What are Gemstone Enhancements?

What are Gemstone Enhancements?

Gemstone enhancements improve the appearance and wearability of gems. Learn about the most commonly used procedures and frequently treated types...
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Gemstone Thermal Properties

Gemstone Thermal Properties

Non-destructive tests are critical for gemologists trying to identify gems. Learn how measuring thermal properties, especially thermal inertia, can help....
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What is Gemstone Pleochroism?

What is Gemstone Pleochroism?

Some gems show pleochroism, two or three different colors depending on the viewing angle. Learn why this occurs and how...
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Gemstone Magnetism: The Forgotten Property

Gemstone Magnetism: The Forgotten Property

Although gemstone magnetism isn't commonly tested, it can help gemologists distinguish similar looking gems. Learn how to analyze this property....
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What is a Trapiche Emerald?

What is a Trapiche Emerald?

Trapiche emerald gems are some of the world's rarest emeralds. Learn where they're found and how their characteristic “spoked wheel”...
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What is Gemstone Luminescence?

What is Gemstone Luminescence?

Gemstone luminescence is a glow that occurs when certain stones are subjected to energy such as UV light. This effect...
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Evaluating Gem Color: Hue, Tone, and Saturation

Evaluating Gem Color: Hue, Tone, and Saturation

Accurately describing gem color is critical to determining a gemstone's value. Learn how to grade hue, tone, and saturation and...
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Understanding Color in Gemology

Understanding Color in Gemology

The color of a mineral or gemstone is one of the primary attributes used for identification,but it is, unfortunately, one...
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