Advanced Gemology Topics

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

Advanced Gemology Topics

  • gemstone color change - stillwellite
    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 answer is pretty complex, a few diagrams can really help.

  • Gemstones and Refraction Liquids

    Liquids with a high refractive index (RI) are used in gemology to evaluate the refractive index of a gem or to separate one from another in a bundle. Another use is to allow a clearer vision of any inclusions in a gem while it is immersed in the…

  • HPHT Diamond Update 

    Step 2: Advanced Gemology Lesson 8 Back to syllabus Synthetic Diamond History High Pressure High TemperatureDiamonds were first synthesized from graphite in the 1950s by the high pressure high temperature (HPHT) process. In…

  • Identifying Inclusions

    Magnification opens the door to a fascinating dimension in gemology: the inner world of inclusions, materials trapped inside gemstones. You’ll see marvels that can rival the beauty and intrigue of the gem itself. On a practical level, identifying…

  • Measuring a Gemstone RI above 1.81

    by Raul Berenguel, PhD The determination of a refractive index (RI) above 1.81 can be a problem for several reasons. While you could use an electronic refractometer to measure a gemstone RI, it would be expensive because the low-cost models do…

  • impurity ions - red beryl
    Impurity Ions and Gemstone Colors 

    I’ve faced many questions about the element chromium (Cr), the red coloration of minerals, and the gemstone red beryl. One of the many causes of color in gems and minerals is impurity ions.

  • gemstone radiation - quartz
    Gemstone Radiation Treatment 

    Most gems on the market today receive various treatments to change their natural colors and create more desirable, salable products. Radiation and heating are the most common treatments, used alone or sometimes in combination with other enhancements.

  • The History of Quartz Treatment

    Recently there have been questions about a treated quartz with a light yellow/green color similar to chrysoberyl. The material is traded in Brazil under the name Ouro Verde. I am actually the one who developed the process. In this process, the gem…

  • 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 properties are also important. They determine a gem’s durability, guide faceters when they cut and set, and help us gemologists identify gemstones.

  • 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 

    Step 2: Advanced Gemology Lesson 12 Back to syllabus Beryl and Tourmaline 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. While…

  • Identifying Garnets Simplified 

    The most complicated part of identifying garnets is distinguishing between the species. The gems in the almandine, pyrope, and spessartite series are particularly difficult separations. However, the following chart will simplify the process once…

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