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Opal

Fireworks. Jellyfish. Galaxies. Lightning. Opal’s shifting play of kaleidoscopic colors is unlike any other gem.

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Cabochon

Most opals are cut as cabochons; this one from Ethiopia weighs 20.86 ct.

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Unique Beauty

The play-of-color displays the entire spectrum over a light gray background.

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Pattern

Bright flashes of color skip across this stone’s surface.

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Hidden Beauty

Opal forms as irregular nodules or seams in volcanic or sedimentary rocks.

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Rare Phenomena

Play-of-color results when light interacts with orderly stacks of spheres.

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Treasure

This opal nodule displays the promise of intense play-of-color.

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Tools

Research

Figure 1. A pattern resembling Chinese characters in an 8.13 ct black opal. Note that blade-like play-of-color patches exist within common opal. Photomicrograph by Makoto Miura; field of view 12.06 mm.
Written Characters in Black Opal

Play-of-color patches in black opal display interesting written character patterns.

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Figure 1. Pedro II is the most important opal source in Brazil. The town is located in the northeast of the state of Piauí, and opal deposits are distributed in an area about 20 km in diameter around the township. The current opal mine is an open-pit operation. Photo courtesy of Prime Gems.
Precious Opal from Pedro II, Brazil

A look at the variety of rough and finished Brazilian opal offered by Prime Gems at the GJX show.

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Figure 2. Rough sample of Chilean blue opal, about 18 cm wide, displaying a dull conchoidal fracture, alternating green and blue bands, some white lenses (milky quartz), and a light brown matrix. Photo by Cristiano Brigida; courtesy of Chilean Rocks and Minerals.
Blue Opal from Chile

An ocean blue variety of opal from Chile was introduced at the 22nd Street show in Tucson.

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The front of the “Blue Boy” chest features two wing-like “conk” wood opal slices from Nevada.
Intarsia Jewelry Box by Nicolai Medvedev and Susan Helmich

Opening day at the AGTA GemFair included the unveiling of the “Treasure Chest II with Blue Boy” intarsia jewelry box.

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Figure 1. A silver brooch containing a large Slovak opal (77 ct, 34.5 × 25 × 13 mm) and 48 diamonds. The opal was initially purchased for Louis XVIII’s personal collection. In 1824, it adorned the clasp of Charles X’s coronation mantle, and around 1853 it was remounted onto this brooch for Empress Eugénie, which has been preserved. Photo by Peter Semrád; courtesy of the National Museum of Natural History in Paris (inventory no. MNHN 87.44).
Slovak Opal: A New Life for a Historical Gem

Reports on the recent production of precious and common opal from a centuries-old locality.

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Figure 1. An 11.68 ct treated phantom opal in which the phantom structure appeared during experiments with various solutions. The sample is shown under daylight through the dome (left) and under halogen lighting through the bottom (right). Photos by Le Ngoc Nang.
A New Treatment: Creating Phantom Structure in Opal

A newly developed treatment creates a phantom structure in opal visually similar to natural phantom opal.

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Figure 1. The Heart of Australia, a 3,510 ct double pseudomorph ikaite-calcite-opal gem specimen, is considered one of the finest ever unearthed. Courtesy of Graeme Dowton.
Rare Double Pseudomorph Ikaite-Calcite-Opal

One of the finest specimens of double pseudomorph ikaite-calcite-opal ever unearthed was on display at the Pueblo Gem & Mineral Show.

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Andrew Cody, one of Australia’s leading opal experts.
In Memoriam: Andrew Cody

The life of one of Australia’s leading opal authorities is remembered.

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Ahmadjan Abduriyim (left) receives the 2021 JAMS award for applied mineralogy.
Ahmadjan Abduriyim Receives JAMS Award for Applied Mineralogy

Ahmadjan Abduriyim receives 2021 JAMS award for his contributions to applied mineralogy.

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“Andamooka matrix opal” as rough, after treatment, and a finished freeform cabochon.
Sugar/Heat-Treated Opal

At the AGTA show, lapidarist James Carpenter explains his use of sugar/heat treatment to enhance opal.

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