Ruby (Synthetic Star - Czochralski) | 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. The Czochralski process of gem synthesis involves the melting of various elements in a platinum crucible. A small gem crystal (called a seed) attached to a rod is then dipped into the melt and slowly pulled away as the crystal grows around the seed. For this reason, the Czochralski method is also known as crystal pulling. 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.
Alternate
Names
Lab Created Star Ruby
Colors
Light To Dark Red, Purple Red

Ruby (Synthetic Star - Czochralski) Classification

Common Name

Ruby (Synthetic Star - Czochralski)

Species

Corundum

Variety

Pulled Synthetic Star Ruby

Colors

Light To Dark Red, 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.

Ruby (Synthetic Star - Czochralski) Optical Properties

Transparency

Semitransparent - 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)

Fluorescence

SWUV: strong red
LWUV: strong red

CCF Reaction

Pleochroism

Unobservable

Dispersion

Comments

Ruby (Synthetic Star - Czochralski) Chemistry & Crystallography

Chemical Name

aluminum oxide

Chemical Formula

Al2O3

Synthesis

Czochralski pulled

Crystal System

Trigonal

Classification

Oxide

Nature

Synthetic

Crystallinity

Crystalline

Comments

Ruby (Synthetic Star - Czochralski) Characteristic Physical Properties

Hardness

9

Streak

White

Specific Gravity

4.1-3.95 Typical:4

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

Stability

Very Good

Fracture

Conchoidal

Cleavage

None

Comments

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