Alexandrite (Synthetic) | Gemopedia

Some gems, like alexandrite, are almost impossible to find in nature today, much less in the sizes and quality people dream of owning. Synthetic alexandrite can be created in a variety of ways including flux growth, Czochralski method, or floating zone method. Synthetic gems have the same chemical, optical, and physical properties of their natural counterparts, but are a more cost-effective alternative to a natural gem.
Colors
Bluish Green In Daylight, Fluorescent Light, Brownish Red To Purple-Red In Incandescent

Alexandrite (Synthetic) Classification

Common Name

Alexandrite (Synthetic)

Species

Chrysoberyl

Variety

Synthetic Alexandrite

Colors

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

Alternate Names

Gemstone Groups

Key Separations

Color change, refractive index, birefringence, pleochroism and spectrum help identify alexandrite, but magnification is important to distinguish synthetic from natural. Natural material might show stepped twin planes, feathers and elongated tubes or needles. Strong red fluorescence is a key indicator of synthetic.

Comments

Alexandrite's spectrum varies by direction, showing a different spectrum in the green direction than in the purple-red pleochroic direction. Cat's-eye synthetic alexandrite is also produced.

Alexandrite (Synthetic) Optical Properties

Transparency

Transparent - Translucent

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

NA

Pleochroism

Trichroic, strong green, orange, and purplish red

Dispersion

Strength: weak fire Value: 0.015

Comments

Alexandrite (Synthetic) Chemistry & Crystallography

Chemical Name

beryllium aluminum oxide

Chemical Formula

BeAl2O4

Synthesis

flux growth, pulled or floating zone

Crystal System

Orthorhombic

Classification

Oxide

Nature

Synthetic

Crystallinity

Crystalline

Comments

Alexandrite (Synthetic) Characteristic Physical Properties

Hardness

8.5

Streak

White

Specific Gravity

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

Toughness

Varies

Inclusions

Flux grown synthetic alexandrite might have metallic platelets from the platinum crucible, veil like inclusions, flux inclusions, flux filled cavities, straight or angular growth lines layers of dust-like inclusions parallel to seed plate.Czochralski method pulled stones will have needle like inclusions, curved striae and small black like gas bubbles.Floating zone or hydrothermal stones will have dark gas bubbles, long flat liquid inclusion and a swirled appearance.

Luster

Bright Vitreous

Stability

Very Good

Fracture

Conchoidal

Cleavage

Good, in one direction

Comments

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