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Gemology
Science, tools, identification, treatment, valuation & grading of gems.
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Gübelin Grades an Exceptional Vietnamese Ruby with "Pigeon's Blood" Color
How does Vietnamese ruby compare to Burmese ruby? Learn about the "Red Treasure" of Vietnam and why even experts can...
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Should You Buy Jewelry on a Cruise?
Are the offers you'll find for jewelry on a cruise ship too good to be true? Learn to look beyond...
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Ammonite Mining in Canada
Beautiful ammolite gems are made from ammonite fossils. Come with Jeff Moriarty of Moriarty’s Gem Art on an ammonite mining...
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An Introduction to Gemology
Gem Formation: How are Gemstones Created?
Gem formation usually involves mineral crystallization and other geological processes. Learn how these affect the gemstone properties gemologists study.
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Gemstone Hardness and Wearability
Gemstone hardness measures resistance to scratching. A gem's wearability grade takes hardness into account, but it’s only one of many...
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A Guide to Gem Classification
Gemologists use several different gem classification methods. Learn how the most common systems work and what they cover as well...
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Gemology Tools
10X Loupe for Gemologists and Jewelers
The 10X loupe is the gemologist's best friend. Learn how to examine gemstones for fractures, inclusions, color, and much more...
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Refractometer Guide, Part 1: Refractive Index Testing
A gem refractometer is the best tool for refractive index testing. Learn how to use this instrument to conduct this...
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Spectroscope Instructions for Novice Gemologists
The spectroscope is one of gemology’s principal tools. Our basic spectroscope instructions will teach you how to operate and calibrate...
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Physical and Optical Properties of Gemstones
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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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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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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Gemstone Testing and Identification
An Introduction to Gem Identification
Gem identification is part detective work, part art. Learn how gemologists can distinguish gem species and determine whether a stone...
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Gem, Mineral, and Rock Scanner Identification Apps Review
How accurate are gem, mineral, and rock scanner identification apps? Our review covers the strengths and weaknesses of over 20...
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Identifying Opal Patterns
Opal connoisseurs all have their favorite opal patterns. Learn how to identify the patterns of these beautiful gems with plenty...
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Synthetic Gemstones
What's the Difference Between Synthetic, Simulated, and Created Gemstones?
What's the difference between synthetic, simulated, and created gemstones? Learn the definitions (and gray areas) of these commonly used terms....
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Identifying Lab-Made Emeralds
Mined emeralds are expensive, so lab-made emeralds are an attractive option for consumers. Learn how these synthetic gems are made...
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Synthetic Gemstone Inclusions
Identifying lab-created gems is a critical skill for gemologists. Learn how to spot the most common synthetic gemstone inclusions.
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Gemstone Treatments
Disclosing Enhancements: A Gemologist's Guide
Disclosing enhancements to gems is a key duty for gemologists. Learn what are the hardest treatments to detect and how...
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Common Gemstone Treatments Cheat Sheet
There are so many common gemstone treatments available today that keeping track of them can be difficult. This list and...
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Aquamarine Color and Heat Treatment
There's more to aquamarine color than blue. Most natural stones start blueish green and are heated to blue. Learn the...
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Advanced Gemology Topics
Impurity Ions and Gemstone Colors
How do gems likes rubies and red beryls get their red color? Learn the role impurity ions play in the...
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HPHT Diamond Treatments
HPHT diamond treatments can only be positively identified with costly equipment. However, you can learn to assess the probability that...
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Gemstone Photomicrography: Photographing Inclusions
Explore the amazing world of gemstone photomicrography. These tips can help you view and photograph spectacular inclusions found inside many...
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The Lighter Side of Gemology
Garnet Symbolism
Garnet symbolism is rich and varied. This gemstone has inspired many legends and popular associations with love, friendship, light, and...
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The World’s Largest Emeralds
Emerald crystals can grow very large. Learn about some of the world’s largest emeralds, whether rough, faceted, or carved.
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Ten Gemstones Rarer than Diamond
If you're looking for something unique for your next jewelry purchase, check out these ten gemstones rarer than diamond. How...
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Gem Tourism
Top Spots for Gem Hunting in the US
Visit one of the top gem hunting spots in the US. Go alone or with the family. A gemology-themed vacation...
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Opal Prospecting and Mining
Headed out to the opal fields? Read on to learn more about opal prospecting and mining, plus some expert tips...
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Desert Prospecting: Discovering California Turquoise
IGS member Richard Edley shares his experiences discovering California turquoise and offers advice on desert prospecting.
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Questions About Gems and Jewelry
Is Lab-Created Alexandrite Real Alexandrite?
Natural alexandrite is popular and rare, which creates a market for synthetics. But is lab-created alexandrite real alexandrite? Learn the...
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Ruby and Sapphire Survey: Where Do You Draw the Line?
Our survey asked for your input on the age-old question: where is the line between ruby and sapphire? The results...
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Is Uranium Glass Safe to Facet?
Uranium glass, or Vaseline glass, is a prized collector's item and is generally safe to handle. But is it safe...
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Reference Charts & Materials
Gemstone Toxicity Table
Gem faceters and jewelry enthusiasts alike should learn about gemstone toxicity. This table has toxicity ratings for 280+ gems, based...
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Table of Refractive Indices and Double Refraction of Selected Gems
Refractive indices and double refraction (birefringence) help gemologists identify gems. The following table lists these values for selected gemstones.
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Specific Gravity Values of Selected Gems
Measuring specific gravity helps gemologists identify gemstones. The following table lists the specific gravity values for a variety of gem...
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