Opal (Synthetic) | Gemopedia

Some gems, like opal, are highly coveted but rare to find, much less in the sizes and quality people dream of owning. Synthetic, or laboratory created jewels, offer you the best of both worlds. You get the beauty of a beloved, rare gemstone, but at a budget friendly price. The term synthetic refers to a man-made material with a natural counterpart. The synthetic crystal replicates the chemical, optical and physical properties of the natural crystal with little or no variation.
Alternate
Names
Gilson Opal
Colors
Orangy Red, Red, Light To Dark Pink, Blue To Grayish Blue, Green To Bluish Green, Orange, Yellow, Light To Dark Brown, Gray, Bluish Gray

Opal (Synthetic) Classification

Common Name

Opal (Synthetic)

Species

Opal

Variety

Colors

Orangy Red, Red, Light To Dark Pink, Blue To Grayish Blue, Green To Bluish Green, Orange, Yellow, Light To Dark Brown, Gray, Bluish Gray

Alternate Names

Gilson Opal

Gemstone Groups

Key Separations

Magnification possibly fluorescence and phosphorescence

Comments

Newer untreated red to orange, gray-blue, white to colorless and gray to black stones have an SG between 2.22 to 2.27. Polymer impregnated stones have an SG between 1.88 to 1.91.

Opal (Synthetic) Optical Properties

Transparency

Transparent - Opaque

Refractive Index

1.43-1.47

Birefringence

Optic Character

NA

Optic Sign

NA

Polariscope Reaction

Singly Refractive (SR) With ADR

Fluorescence

SWUV: Variable
LWUV: Variable

CCF Reaction

Pleochroism

None

Dispersion

Comments

Opal (Synthetic) Chemistry & Crystallography

Chemical Name

silica

Chemical Formula

SiO2.nH2O

Synthesis

chemical precipitation with controlled hydrostatic pressure

Crystal System

NA

Classification

Silicate

Nature

Synthetic

Crystallinity

Amorphous

Comments

Opal (Synthetic) Characteristic Physical Properties

Hardness

4.5-6

Streak

Specific Gravity

1.97-2.2

Toughness

Varies

Inclusions

You can see the columnar structure of synthetic opal when viewed from the side. The stones play of color patterns often look like snake skin or chicken wire under magnification. Stones with vivid colors are probably polymer impregnated.

Luster

Vitreous

Stability

Poor

Fracture

Conchoidal, Uneven

Cleavage

None

Comments

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