Gemstone Thermal Properties
Non-destructive tests are critical for gemologists trying to identify gems. Learn how measuring thermal properties, especially thermal inertia,…
What is Gemstone Pleochroism?
Some gems show pleochroism, two or three different colors depending on the viewing angle. Learn why this occurs and how it helps gemologists identify…
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.…
Descriptive Crystallography for Gemologists
Crystallography is the study of crystalline solids. Learn the most common terms gemologists use to describe the structure of crystal gems.
Gemstone Optics: The Basics
Accurately measuring optical properties is critical for identifying gemstones. This article covers the basic terminology and concepts of gemstone…
What is Gemstone Cleavage?
Gemstone cleavage is a break in a crystal along internal planes. Learn the science behind this and the difference between cleavage, fracture,…
What is Gemstone Luminescence?
Gemstone luminescence is a glow that occurs when certain stones are subjected to energy such as UV light. This effect can help gemologists identify…
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 others occur…
Gemstone Optical Properties
Rarely do we think of the scientific definition of light or its properties. However, light plays a critical role in gemology. You must first understand…
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 avoid some common…
Gemstone Color Change Phenomena
Frequently, people ask me to explain how gemstone color change works. Some stones can change color under different light sources. Although the…
What are Gemstone Enhancements?
Gemstone enhancements improve the appearance and wearability of gems. Learn about the most commonly used procedures and frequently treated…
Phenomenal Gems – Unique Phenomena in Gemstones
Phenomenal gems seem to do magical things with light. Learn the optical effects behind these displays and how to judge the value of these beautiful…
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…
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 of the least diagnostic…
IGS Newsletter