Physical and Optical Properties of Gemstones

Learn how gemstone optical properties, like refractive index and pleochroism, help gemologists identify gems and lapidaries choose cuts.

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

Non-destructive tests are critical for gemologists trying to identify gems. Learn how measuring thermal properties, especially thermal inertia,…

Some gems show pleochroism, two or three different colors depending on the viewing angle. Learn why this occurs and how it helps gemologists identify…

Although gemstone magnetism isn’t commonly tested, it can help gemologists distinguish similar looking gems. Learn how to analyze this property.…

Trapiche emerald gems are some of the world’s rarest emeralds. Learn where they’re found and how their characteristic “spoked wheel” patterns…

Crystallography is the study of crystalline solids. Learn the most common terms gemologists use to describe the structure of crystal gems.

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

Gemstone cleavage is a break in a crystal along internal planes. Learn the science behind this and the difference between cleavage, fracture,…

Gemstone luminescence is a glow that occurs when certain stones are subjected to energy such as UV light. This effect can help gemologists identify…

Learn the difference between allochromatic and idiochromatic gems and why some gem species can occur in many color varieties and others occur…

The optical properties of gems attract our eyes and can give a cut stone a unique character. However, gemstone physical properties are also important.…

Accurately describing gem color is critical to determining a gemstone’s value. Learn how to grade hue, tone, and saturation and avoid some common…

Frequently, people ask me to explain how gemstone color change works. Some stones can change color under different light sources. Although the…

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 are hard to make with conventional color-order systems. Learn how recent colorimetry tech advances have improved…

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…