Alexandrite (Synthetic Cat's Eye) | Gemopedia

The term cat's eye, or chatoyancy, is used to describe a phenomenal optical property in gemstones, in this case synthetic chrysoberyl. The effect, when present, appears as a bright, narrow slit similar to the pupils in the eyes of your favorite feline. This phenomenon is caused by parallel fibrous or needle-like inclusions that interfere with the passage of light throughout the crystal, scattering and reflecting light back to the viewer as a thin line. Chatoyant synthetic chrysoberyl is particularly incredible because it exhibits two rare phenomena in gemstones: both the cat's eye affect and color change. The term synthetic refers to a man-made material with a natural counterpart that shares the same (or nearly identical) chemical, optical, and physical properties. Synthetic color change chrysoberyl presents gem lovers with an opportunity to own the stunning color change effect so prized in gems.
Colors
Bluish Green In Daylight, Fluorescent Light, Brownish Red To Purple-Red In Incandescent

Alexandrite (Synthetic Cat's Eye) Classification

Common Name

Alexandrite (Synthetic Cat's Eye)

Species

Chrysoberyl

Variety

Synthetic Cat's-Eye Alexandrite

Colors

Bluish Green In Daylight, Fluorescent Light, Brownish Red To Purple-Red In Incandescent

Alternate Names

Gemstone Groups

Key Separations

Magnification, fluorescence, cat's-eye appearance and color change, RI, SG and spectrum. Strong red fluorescence might be an indicator of synthetic.

Comments

Alexandrite (Synthetic Cat's Eye) Optical Properties

Transparency

Semitransparent

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: moderate to strong red
LWUV: moderate to strong red

CCF Reaction

red

Pleochroism

Unobservable

Dispersion

Strength: weak fire Value: 0.015

Comments

Alexandrite (Synthetic Cat's Eye) Chemistry & Crystallography

Chemical Name

beryllium aluminum oxide

Chemical Formula

BeAl2O4

Synthesis

pulled and floating zone

Crystal System

Orthorhombic

Classification

Oxide

Nature

Synthetic

Crystallinity

Crystalline to Aggregate

Comments

Alexandrite (Synthetic Cat's Eye) Characteristic Physical Properties

Hardness

8.5

Streak

White

Specific Gravity

3.71-3.75 Typical:3.73

Toughness

Excellent

Inclusions

Pulled synthetic cat's-eye alexandrite might show needles and curved striae. Floating zone synthetic stones can have gas bubbles and show a swirled appearance. Undulating growth lines can be seen in some stones.

Luster

SubAdamantine

Stability

Very Good

Fracture

Conchoidal

Cleavage

Good, in one direction

Comments

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