Chrysoberyl | Gemopedia

Chrysoberyl is the name of a mineral as well as three different gem varieties--two of which are widely accepted as some of the most rare and valuable of all phenomenal gems. The gem commonly known as chrysoberyl is a yellowish-green, brownish-yellow, or colorless transparent to translucent mineral that is usually faceted into gems and generally considered a collector's stone. While not often set in jewelry, its characteristics make it ideal for such use. When chrysoberyl displays color-change properties, it is known as alexandrite, and when it exhibits chatoyancy, it is known as cat's eye chrysoberyl.
Colors
Yellow To Yellowish Green, Greenish Brown, Bluish Green

Chrysoberyl Classification

Common Name

Chrysoberyl

Species

Chrysoberyl

Variety

Colors

Yellow To Yellowish Green, Greenish Brown, Bluish Green

Alternate Names

Gemstone Groups

Key Separations

refractive index, birefringence, pleochroism and spectrum. Spectrum should reflect a strong diagnostic band at 444nm.

Comments

Phenomenal chrysoberyl may exhibit chatoyancy, in which case it is classified as "cat's-eye chrysoberyl." Misnomer: oriental chrysolite.

Chrysoberyl Optical Properties

Transparency

Transparent - Opaque

Refractive Index

1.746-1.755
Tolerance:(+0.004/-0.006)

Birefringence

0.008-0.01

Optic Character

Biaxial

Optic Sign

Positive

Polariscope Reaction

Doubly Refractive (DR)

Fluorescence

SWUV: Inert to yellowish green in yellow and greenish stones
LWUV: Could be red for "mint" chrysoberyl

CCF Reaction

Pleochroism

Trichroic, weak

Dispersion

Strength: weak fire Value: 0.015

Comments

Chrysoberyl Chemistry & Crystallography

Chemical Name

beryllium aluminum oxide

Chemical Formula

BeAl2O4

Synthesis

Crystal System

Orthorhombic

Classification

Oxide

Nature

Natural

Crystallinity

Crystalline

Comments

Chrysoberyl Characteristic Physical Properties

Hardness

8.5

Streak

White

Specific Gravity

3.71-3.75 Range:+/-0.02 Typical:3.73

Toughness

Varies

Inclusions

Transparent green and yellow chrysoberyl are type I clarity stones. Stones might show twinning planes, feathers, fingerprints, silk, elongated tubes and needles.

Luster

Bright Vitreous

Stability

Very Good

Fracture

Conchoidal

Cleavage

Good, in one direction

Comments

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