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Figure 12. Rough and cut iolite from Blue Bear. From left to right, the faceted stones weigh 1.24, 0.48, 0.48, and 0.88 ct. Photo by Philippe Belley.

Iolite from the Thor-Odin Dome, British Columbia, Canada: Geology, Chemical Composition, Inclusions, and Cause of Chatoyancy

Philippe M. Belley, November 3, 2023

Reports on the geological setting and gemological properties of violet-blue gem cordierite from new deposits located in British Columbia.

Figure 2. Rectangular step-cut green beryl from the Volyn pegmatite, 190.00 ct and 28.55 × 39.02 × 21.71 mm, with a rough unpolished table containing etch pits. Faceting and photo by Konstantyn Zalizko.

Etch Pits in Heliodor and Green Beryl from the Volyn Pegmatites, Northwest Ukraine: A Diagnostic Feature

Gerhard Franz, Oleksii A. Vyshnevskyi, Volodymyr M. Khomenko, Peter Lyckberg, and Ulrich Gernert, November 3, 2023

Examines dissolution features of heliodor and green beryl from a Ukrainian pegmatite field and offers criteria to distinguish them from samples found in other localities.

Figure 1. Mineral inclusions in diamond. This connected pair of green clinopyroxene and orange garnet indicates that diamond growth occurred within an eclogitic mantle host rock. Photomicrograph by Nathan Renfro; field of view 2 mm.

Eclogite: Diamond-Encrusted Ancient Seafloor

Evan M. Smith and Matthew F. Hardman, November 3, 2023

Explores eclogitic diamonds, which make up a significant portion of the gem diamond market, and what they reveal about Earth’s dynamic processes.

Figure 1. These exceptional natural yellow sapphires from Madagascar (2.1–2.6 ct) represent both the Fe<sup>3+</sup> chromophore and the trapped hole paired with Fe<sup>3+</sup>. Photo by Ronnakorn Manorotkul/Lotus Gemology; courtesy of GemFever.

Yellow Sapphire: Natural, Heat-Treated, Beryllium-Diffused, and Synthetic

John L. Emmett, Ungkhana Atikarnsakul, Jennifer Stone-Sundberg, and Supharart Sangsawong, November 3, 2023

Investigates the various chromophores responsible for color in four types of yellow sapphire.

Figure 1. Faceted Oregon sunstone crystals (2.75–7.71 ct) representing the variety of colors observed. Photo by Adriana Robinson. Courtesy of the GIA Museum. Gifts of Western Ventures (pear shape), Dust Devil Mining Co. (oval), and John and Laura Ramsey (emerald cut on the far right).

Special Colors and Optical Effects of Oregon Sunstone: Absorption, Scattering, Pleochroism, and Color Zoning

Shiyun Jin, Aaron C. Palke, Nathan D. Renfro, and Ziyin Sun, November 3, 2023

Details the colors and optical effects caused by metallic copper inclusions in this gem-quality feldspar.

Figure 1. A good-quality 88.25 ct “chameleon” amber with a red bodycolor displaying a vivid green fluorescence color that appears to float on the surface. Photo by Yan Li.

The Special Color Effect in “Chameleon” Amber

Jinfeng Yang, Yan Li, and Youzhi Liang, November 3, 2023

An examination of three Burmese chameleon amber specimens using 3D fluorescence spectroscopy.

A well-formed colorless breyite crystal reminiscent of a stone making a splash in water. Photomicrograph by Aprisara Semapongpan; field of view 1.07 mm.

Breyite in Diamond

Aprisara Semapongpan, November 3, 2023

A colorless transparent crystal inclusion in diamond is reminiscent of a stone splashing in water.

Figure 1. Table (left) and pavilion (right) views of a chameleon diamond with visible trigons and tetragons. The trigons and tetragons are shown in more detail in figures 2 and 3. The diamond measures 1.28 cm in length. Photo by Adriana Robinson.

Etch Features Reveal the Morphology of Diamond

Mei Yan Lai and Matthew Hardman, November 3, 2023

Trigons and tetragons observed in a chameleon diamond indicate both octahedral and cubic growth.

Figure 1. Iridescent andradite samples (25 ct and 125 ct) from the Lindong area of Inner Mongolia, China. As shown in the left photo, sample G-1 displays iridescence on the (211) plane but not on the (110) plane. Photos by Jiuchang Yang.

A Newly Discovered Iridescent Andradite from Inner Mongolia, China

Jiuchang Yang, Quanli Chen, Fengshun Xu, Yan Li, and Xianyu Liu, November 3, 2023

The first report of iridescent andradite from China.

Bladed crystals of columbite radiate from a central point in colorless topaz. The mirror-like surfaces allow for reflections of neighboring blades, as seen in the top left crystal. Photomicrograph by Tyler Smith; field of view 2.90 mm.

Spray of Columbite Crystals in Topaz

Tyler Smith, November 3, 2023

A cluster of bladed columbite crystals is identified in colorless topaz.

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