Advanced gemology topics on a wide variety of technical subjects such as gemstone treatments and inclusions.

gemstone color change - stillwellite
Gemstone Color Change Phenomena

Why do certain gems change color under different lights? Explore gemstone color change phenomena and the difference between natural and artificial light.

gemstone refraction liquids - immersion test
Gemstones and Refraction Liquids

Gemologists use refraction liquids to identify gemstone refractive indices (RI). Learn about the properties of these liquids and safe RI testing procedures.

HPHT Diamond Update

Gemologists are seeing more and more HPHT diamonds. While detection equipment is costly, you can assess the likelihood of treatment without it.

Identifying Inclusions

Identifying inclusions can help gemologists identify gems, but it’s a hard skill to master. Our 4-part series on gemstone inclusions will get you started.

A microscope adapted for measuring OTL gemstone RIs.
How to Measure an OTL Gemstone Refractive Index

Measuring “over the limit” (OTL) refractive indices can help distinguish diamonds from simulants. You can do this with a simple upgrade to your microscope.

impurity ions - red beryl
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 coloration of these and other gemstones.

gemstone radiation - quartz
Gemstone Radiation Treatment

Gemstone radiation is a common but little understood technique for altering gem colors. Learn how it's done and what gems usually receive this treatment.

The History of Quartz Treatment

Learn about the history of quartz treatment, including why it took so long to treat quartz with any consistency, in this informative article.

gemstone physical properties -
Gemstone Physical Properties

Learn how gemstone physical properties, like hardness and heat sensitivity, affect a gem's durability and cut and help gemologists with identifications.

quartz color treatments - irradiated yellow quartz
Quartz Color Treatments

Quartz color treatment results vary due to the stone's origin. Learn the effects you can achieve with different materials and radiation and heat techniques.

emerald enhancements - jardin
Understanding Emerald Enhancements and Treatments

Emerald enhancements involve a variety of different types of fillers, impregnations, and dyes. These treatments can improve the beauty of emeralds.

Gemstone photomicrography - Mexican opal
Gemstone Photomicrography: Photographing Inclusions

Explore the amazing world of gemstone photomicrography. These tips can help you view and photograph spectacular inclusions found inside many gems.

Identifying Inclusions of Specific Gems

Both beryl and tourmaline develop hollow, or "growth" tubes. The gem cutter sees many more of these than the gemologist does, as most are cut away.

Identifying Garnets Simplified

Identifying garnets by species is complicated. Learn how to use refractive index, hue, and absorption spectrum readings to simply the separation process.