The Summer 2025 issue of Gems & Gemology (Volume 61, Number 2) offers a clear and up-to-date look at key topics in gemology. Highlights include an analysis of optical effects in gemstones, an in-depth study of granitic pegmatites as sources of gemstones, and a profile of the extraordinary career of master cutter Ben Kho.
In “Structures Behind the Spectacle: A Review of Optical Effects in Phenomenal Gemstones and Their Underlying Nanotextures”, Shiyun Jin, Nathan D. Renfro, Aaron C. Palke, and James E. Shigley provide a comprehensive review of optical effects in gemstones, explaining their physical and mineralogical foundations. Opalescence, iridescence, asterism, adularescence, labradorescence, and other phenomena are examined in detail in light of the nanostructures that produce them. The authors classify these effects according to dimensionality: zero-dimensional nanoparticles that create a milky appearance (diamond, corundum); one-dimensional needle-like inclusions responsible for cat’s-eye and star effects (chrysoberyl, garnet); two-dimensional platelets producing iridescence and sheen in feldspars; and three-dimensional crystals in opal, which generate the famous play-of-color. Modern analytical techniques — XRD, SEM, and TEM — have allowed researchers to observe these structures with unprecedented detail, bringing academic research ever closer to applied gemology.
The article “Colored Stones Unearthed: Gem Granitic Pegmatites”, edited by Aaron C. Palke and James E. Shigley, provides a broad overview of the geology and mineralogy of granitic pegmatites, important sources of gemstones and minerals. Pegmatites, formed through the crystallization of water- and volatile-rich residual magmatic fluids, are renowned for their large crystals and for hosting significant minerals such as tourmaline, beryl, spodumene, topaz, and garnet. The analysis emphasizes not only their role in gemology but also their economic and industrial importance, highlighting materials like quartz, feldspar, and mica, and offering a global perspective on their distribution and scientific value.
In “Ben Kho: From Rough Beginnings to Brilliant Mastery”, Jennifer Stone-Sundberg chronicles the life of gem cutter Ben Kho, a prominent figure on the international stage. From the hardships he faced in Cambodia during the years of the Killing Fields to his fresh start in the United States, Kho’s story is a testament to resilience and talent. His skill in cutting complex stones, such as rhodochrosite, has earned him prestigious awards, including the AGTA Cutting Edge Buyer’s Choice Award for a 12.88-carat rhodochrosite. His career demonstrates how artisanal mastery and technical knowledge can combine to achieve excellence.
The full issue of Gems & Gemology is available on the GIA website.
