Fall 2023 G&G Available Now

Erica Zaidman

November 3, 2023

The Fall issue of Gems & Gemology has a wide range of colored stone topics in store, from the cause of color in yellow sapphire to the characterization of Oregon sunstone, Ukrainian beryl, and British Columbian iolite. In addition to the four feature articles and our quarterly sections, we see the return of Diamond Reflections and the 2023 G&G Challenge results.

YELLOW SAPPHIRE: NATURAL, HEAT-TREATED, BERYLLIUM-DIFFUSED, AND SYNTHETIC

Dr. John Emmett and fellow researchers share their in-depth study of the various chromophores responsible for color in natural, heat-treated, beryllium-diffused, and synthetic yellow sapphire. Their results reveal that Fe³⁺, a trapped hole associated with iron (h^•-Fe³⁺), or a combination of the two are involved in the coloration of natural and treated yellow sapphire, while color in synthetic yellow sapphire is attributed to the Ni³⁺ chromophore or a combination of Ni³⁺ and Cr³⁺.

SPECIAL COLORS AND OPTICAL EFFECTS OF OREGON SUNSTONE: ABSORPTION, SCATTERING, PLEOCHROISM, AND COLOR ZONING

Dr. Shiyun Jin and colleagues investigate the special colors and optical effects caused by metallic copper inclusions in Oregon sunstone using samples from various mines. Their study covers the absorption and scattering of light as well as pleochroism and color zoning in this increasingly popular gemstone from the United States.

ETCH PITS IN HELIODOR AND GREEN BERYL FROM THE VOLYN PEGMATITES, NORTHWEST UKRAINE: A DIAGNOSTIC FEATURE

The Volyn pegmatite field in Ukraine is known for the production of green beryl and the yellow beryl variety heliodor. Led by Dr. Gerhard Franz, researchers present their study examining the dissolution features of Ukrainian heliodor and green beryl and offer criteria to distinguish them from samples found in other localities.

IOLITE FROM THE THOR-ODIN DOME, BRITISH COLUMBIA, CANADA: GEOLOGY, CHEMICAL COMPOSITION, INCLUSIONS, AND CAUSE OF CHATOYANCY

Dr. Philippe Belley reports on gem-quality cordierite from two recently discovered occurrences in British Columbia—Blue Arrow and Blue Bear. The paper details the geological setting and gemological properties of this violet-blue iolite and notes the potential for future discoveries in the area.

LAB NOTES

GIA’s global laboratory staff share their latest findings in the Lab Notes section, including two traditional Indian pearl submissions to the Mumbai lab—a Bombay pearl bunch and two pearl nose rings—and a ruby filled with zinc glass examined in the Carlsbad lab.

MICRO-WORLD

The Micro-World section continues to highlight fascinating gem inclusions with an intricate moiré pattern in purple spinel, blade-like magnetite inclusions in peridot, brown matrix in an Armenian turquoise sphere mimicking planet Earth, and more.

DIAMOND REFLECTIONS

Diamond Reflections returns to explore diamonds formed within eclogitic mantle host rocks and what they reveal about Earth’s dynamic processes.

GEM NEWS INTERNATIONAL

Finally, GNI contributors report on new occurrences of basalt-related gems in southeast Vietnam, an assessment of responsible pearl farming in Australia, the opening of the Gübelin Gem Museum in Switzerland, and more.