Synthetic Star Ruby | Gemopedia

Synthetic star ruby exhibits the optical phenomenon called asterism, a star-like pattern created on the surface of a gemstone when light encounters parallel fibrous, or needle-like, inclusions within its crystal structure. Light that strikes the inclusions within the gem reflects off of the inclusions, creating a narrow band of light. When two or more intersecting bands appear, a star pattern is formed. Depending on the crystal, the star may have four, six, or even twelve rays. When only one band forms, it is classified as a cat's eye, As a synthetic gemstone, this jewel exhibits the same chemical, optical and physical properties as natural star ruby.
Alternate
Names
Lab Created Star Ruby
Colors
Light To Dark Red
, Purple Red

Synthetic Star Ruby Classification

Common Name

Synthetic Star Ruby

Species

Synthetic Corundum

Variety

Pulled Synthetic Star Ruby

Colors

light to dark red or purple red

Alternate Names

lab created star ruby

Gemstone Groups

Key Separations

Magnification, RI and maybe fluorescence

Comments

Stones typically have flat bases and are well cut calibrated cabochons. Stones will have brighter colors than natural rubies.

Synthetic Star Ruby Optical Properties

Transparency

Semitransparent To Opaque

Refractive Index

1.762-1.77 Tolerance: (+0.009/-0.005)

Birefringence

0.008-0.01

Optic Character

uniaxial

Optic Sign

negative

Polariscope Reaction

doubly refractive (DR) or AGG depending on transparency

Fluorescence

SWUV: strong to very strong red with moderate to strong chalky blue-white overtone
LWUV: very strong red

CCF Reaction

Pleochroism

Value: usually weak red-orange to purplish red to none depending on transparency

Dispersion

Comments

Synthetic Star Ruby Chemistry & Crystallography

Chemical Name

aluminum oxide

Chemical Formula

Al2O3

Synthesis

Czochralski pulled

Crystal System

Trigonal

Classification

Oxide

Nature

Synthetic

Crystallinity

Crystalline

Comments

Synthetic Star Ruby Characteristic Physical Properties

Hardness

9

Streak

white

Specific Gravity

4.1-3.95

Toughness

Excellent

Inclusions

Pulled synthetic star ruby will have extremely fine needles that produce a slightly wavy natural looking 6-rayed star. The stones typically show low-relief curved striae or wavy growth. Sometimes bluish white smoke-like swirls and small round or distorted blackish gas bubbles are seen in stones.

Luster

Subadamantine To Vitreous

Stability

Very Good

Fracture

Conchoidal

Cleavage

None, May Show Parting On Twinned Stones

Comments

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