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A “sun spangle” created in amber as a result of rapid cooling. Photomicrograph by Aamir Sayed; field of view 1.5 mm.

“Sun Spangle” in Amber

Aamir Sayed, January 26, 2024

Heat treatment leaves a stunning circular stress fracture in amber.

HPHT-treated blue diamond (left) with ragged-looking graphitization around an inclusion (center) and high-order interference colors with crossed-polarizing filters (right).

Large HPHT-Treated Blue Type IIb Diamond

Evan M. Smith, Paul Johnson, and Kyaw Soe Moe, August 9, 2018

A look at the color zoning exhibited by the largest HPHT-treated blue diamond graded by GIA.

Figure 1. This 2.20 ct Fancy Deep brownish orange treated HPHT-grown diamond owes its distinctive appearance to multiple defect concentrations created within the various growth sectors. Photo by Diego Sanchez.

Treated HPHT Laboratory-Grown Diamond with Dramatic Color Zoning

Sally Eaton-Magaña and Taryn Linzmeyer, January 26, 2024

A Fancy Deep brownish orange treated HPHT-grown diamond exhibits multiple defect concentrations in various growth sectors.

Article

Fall 2023 G&G Available Now

Erica Zaidman, November 3, 2023

An overview of the Fall 2023 Gems & Gemology content.

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.

An 84.90 ct sphere of Armenian turquoise measuring 23.70 × 23.88 × 23.91 mm displays a striking resemblance to planet Earth. Left: Diffuse fiber-optic lighting allows the face of the stone to be seen in full. Right: Pinpoint fiber-optic lighting creates an appearance of day and night cast onto Earth. Gifted to GIA’s colored stone reference collection by Gemfab CJSC. Photos by Britni LeCroy.

Turquoise Planet Earth

Britni LeCroy, November 3, 2023

A sphere of Armenian turquoise with natural brown matrix material mimics planet Earth.

Figure 1. An unusual ruby with coloring reminiscent of a nebula found in the depths of outer space. Photo by Adriana Robinson.

“Nebula” Inclusion in Ruby Beryllium-Diffused to Heal Fractures

Michaela Damba, November 3, 2023

Fingerprints resulting from a flux-assisted heating process give a purple-red ruby a unique appearance.

Figure 1. The etch channel in this CVD laboratory-grown diamond extends across the table facet into the crown. Photomicrograph by Elina Myagkaya; field of view 7.19 mm.

CVD “Etch” Channel

Elina Myagkaya, November 3, 2023

The first report of an etch channel–like structure in a CVD laboratory-grown diamond submitted to GIA.

Figure 2. Sri Lankan sample no. 2801 a much stronger yellow coloration was generated at 1550°C, thickness 3.748 mm, 190 ± 41 ppma Fe.

Heat Treatment Effects on the Behavior of the 3161 cm^–1 Feature in Low-Iron Metamorphic Yellow Sapphire

Ungkhana Atikarnsakul and John L. Emmett, November 10, 2021

This study examines FTIR spectra of yellow sapphire heat treated in an oxidizing atmosphere to deepen its color.

These rubies were determined to be glass filled, partly due to the use of the DiamondView.

Separating Glass-Filled Rubies Using the DiamondView

Larry Tai-An Lai, August 9, 2018

The DiamondView instrument is able to identify glass as the filler in a pair of heart-shaped rubies.

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