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Sapphire

The name “sapphire” can also apply to any corundum that’s not ruby red, another corundum variety.

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A view through the table of a padparadscha sapphire displayed this jagged suspended crystal, likely a metal sulfide, featuring a rare texture. Photomicrograph by Courtney Robb; field of view 2.90 mm.

Spiky Inclusion in Padparadscha Sapphire

Courtney Robb, January 26, 2024

An inclusion with a metallic luster is observed in a pinkish orange padparadscha sapphire.

A greenish blue octahedral crystal of gahnospinel found in Sri Lankan blue sapphire. Photomicrograph by Yusuke Takamura; field of view 3.81 mm.

Octahedral Gahnospinel Crystal in Sri Lankan Blue Sapphire

Yusuke Takamura, January 26, 2024

A rare octahedral gahnospinel crystal is observed in Sri Lankan sapphire.

Figure 1. Various negative crystals in pink sapphire from Sri Lanka (A, enlarged in B) and fingerprints in blue sapphire from Burma (C, enlarged in D). Image B shows bubbles in flat negative crystals, and the center negative crystal in D has a bubble. Photomicrographs by Momo Matsumura (A and B) and Shunsuke Nagai (C and D); fields of view 4.05 mm (A), 8.15 mm (B), 8.47 mm (C), and 1.71 mm (D).

FTIR Identification of Carbon Dioxide Fluids in Sapphire

Kazuko Saruwatari, January 26, 2024

FTIR spectroscopy shows that the existence of carbon dioxide gas bubbles in a negative crystal in sapphire is no longer proof of the absence of heat treatment.

The rectilinear zigzag-patterned fingerprint in this 3.21 ct blue sapphire shows beautiful vibrant colors, indicating a Sri Lankan origin. Photomicrograph by Yuxiao Li; field of view 4.45 mm.

Zigzag Fingerprint in Sri Lankan Sapphire

Yuxiao Li, November 3, 2023

Fiber-optic illumination reveals rectilinear zigzag-patterned films with vibrant colors in a blue sapphire.

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.

$This scene of an iron stain and numerous curved lines showing rainbow colors in a fracture resembles a scene from the night sky viewed through a telescope rather than a microscope. Photomicrograph by Charuwan Khowpong; field of view 2.85 mm.$

Night Sky in Yellow Sapphire

Charuwan Khowpong, August 4, 2023

Fiber-optic light creates a night sky scene in a yellow sapphire from Madagascar.

This pristine hexagonal platelet of graphite was seen in a pink sapphire from Sri Lanka. Photomicrograph by Jeffrey Hernandez; field of view 1.99 mm.

Pink Sapphire with Graphite Inclusion

Jeffrey Hernandez, August 4, 2023

A hexagonal platelet of graphite is discovered in a pink sapphire from Sri Lanka.

Negative crystals arrayed in an arrow-like pattern. Photomicrograph by Suwasan Wongchacree; field of view 1.07 mm.

Arrow-Patterned Negative Crystals in Sapphire

Piradee Siritheerakul and Tao Shiu Hei, May 23, 2023

Examination of a sapphire reveals negative crystals arrayed in an arrow-like pattern.

Figure 1. Part of the suite of sapphires studied for this project (weighing 0.23–1.41 ct). Photo by Sasithorn Engniwat; courtesy of Greenland Ruby.

Color Study of Fancy Sapphire from Greenland

Wim Vertriest, Charuwan Khowpong, Polthep Sakpanich, and Martin Viala, May 23, 2023

The Bangkok laboratory identifies the chromophores responsible for the fancy colors observed in treated sapphire from Aappaluttoq, Greenland.

Figure 1. Top production from Rock Creek from the 2021 mining season, in rough and cut form. The rough stones range from 10.05 to 67.15 ct and the faceted stones from 3.09 to 12.18 ct. The yellow sapphire at top center was named the Yellowstone sapphire and is part of the Somewhere in the Rainbow collection. For the faceted stones, the blue stone on the left and the two blue stones on the bottom are heated, while the others are unheated. Note that one of the rough stones is missing in the faceted stone layout. Photos by Robert Weldon; courtesy of Potentate Mining, LLC.

Gemological Characterization of Montana Sapphire from the Secondary Deposits at Rock Creek, Missouri River, and Dry Cottonwood Creek

Aaron C. Palke, Nathan D. Renfro, Jeffrey R. Hapeman, and Richard B. Berg, May 23, 2023

Examines the mining history and geological characteristics of the three secondary sapphire deposits in the state of Montana, as well as the properties of these sapphires (unheated and heat-treated).

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