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Alexandrite

Green in sunlight. Red in lamplight. Color-changing alexandrite is nature’s magic trick.

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Chrysoberyl Variety

Alexandrite is the color-change variety of the mineral chrysoberyl.

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Green by Day

Alexandrite is bluish green in daylight or fluorescent light.

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Red by Night

Alexandrite is purplish red in incandescent light or candlelight.

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Star-shaped Twin

This alexandrite specimen is made up of three interpenetrant crystals.

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Brazilian Gem

Brazil is one of the most important alexandrite sources.

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Re-entrant Angle

Notches marking the edge of each crystal are called re-entrant angles.

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Alexandrite (53)
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XClear Selections
This 0.69 ct alexandrite showed a stellate structure due to cyclic crystal twinning and pleochroism, producing a kaleidoscope effect when rotated. These photomicrographs were taken with a single polarizer placed above the stone and a white diffuser below the stone to highlight the color. Photomicrographs by Makoto Miura; field of view 9.80 mm.
“Kaleidoscope” in Alexandrite

Makoto Miura, January 26, 2024

Pleochroic colors caused by cyclic twinning produce a kaleidoscope effect in alexandrite.

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Figure 1. Top: Negative crystal in an alexandrite containing a fluid and crystals at room temperature. Bottom: Below 31.2°C, multiple gas bubbles appear. Photomicrographs by Jamie Price; field of view 1.99 mm.
Three-Phase Inclusion in Alexandrite

Jamie Price, May 23, 2023

Examination of alexandrite reveals three phases of matter within a single inclusion suite.

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A group of rings featuring alexandrite from Brazil
Geographic Origin Determination of Alexandrite

Ziyin Sun, Aaron C. Palke, Jonathan Muyal, Dino DeGhionno, and Shane F. McClure, January 31, 2020

The geographic source of this rare color-change gem has a significant impact on value. Trace element chemistry profiles allow GIA to accurately determine origin for alexandrite from several countries.

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Field gemologists sort through gem gravel in Myanmar
Field Gemology: Building a Research Collection and Understanding the Development of Gem Deposits

Wim Vertriest, Aaron C. Palke, and Nathan D. Renfro, January 31, 2020

With more than 90 field expeditions on six continents since 2008, GIA has accumulated over 22,000 colored stone reference samples. This extensive collection of colored stones with known origins supports GIA’s research on geographic origin determination.

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Gemstone classics from sources old and new
The Geographic Origin Dilemma

Shane F. McClure, Thomas M. Moses, and James E. Shigley, January 31, 2020

An overview of the geographic origin complexities facing the gem and jewelry industry today.

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A large group of people outside on GIA’s Carlsbad, California campus.
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Guardians of Trust: GIA’s Innovative Research, Instruments and Services

Russell Shor, September 20, 2019

GIA’s services and instruments have grown in importance and impact as new gem treatments and laboratory-grown gems enter the market.

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Interference figures in faceted alexandrite
Pleochroism and Color Change in Faceted Alexandrite: Influence of Cut and Sample Orientation

Karl Schmetzer, May 15, 2019

Shows how alexandrite’s color and color change are affected by cut and the orientation of table facets.

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Alexandrite cabochon in fluorescent (left) and incandescent light (right).
Cat’s-Eye Alexandrite with Unique Inclusion Pattern

Makoto Miura and Yusuke Katsurada, January 26, 2018

Examination of a chatoyant alexandrite cabochon.

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Copper-bearing tourmaline acquired on the secondary market.
Importance of the Secondary Market for Fine Gems

Duncan Pay, May 8, 2017

Exceptional gems that are recirculated in the gem market make an impact at the Tucson shows.

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Three pieces of labradorite with yellow, blue and green flashes of color.
Article
Optical Effects of Phenomenal Cabochons

Sharon Bohannon, November 10, 2016

Learn how the structure, inclusions and properties of some gemstones interact with light to create unusual visual effects.

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