Opal Doublet | Gemopedia

An opal doublet is an assembled gem that consists of a thin slice of natural opal attached to a second layer of material with a bonding agent. The types of materials used for opal doublets vary considerably but may include ironstone, sandstone, black plastic or quartz. Opal doublets often provide a more affordable alternative to solid opals and are often used today for mass-produced jewelry.
Colors
Variety Of Colors

Opal Doublet Classification

Common Name

Opal Doublet

Species

Opal Doublet

Variety

Colors

Variety Of Colors

Alternate Names

Gemstone Groups

Key Separations

Appearance and magnification

Comments

The base of opal doublets can be made of potch opal, dyed black chalcedony, glass or other matrix materials.

Opal Doublet Optical Properties

Transparency

Semitranslucent - Opaque

Refractive Index

1.45
Tolerance:-0.25

Birefringence

Optic Character

NA

Optic Sign

Polariscope Reaction

Singly Refractive (SR)

Fluorescence

SWUV:
LWUV:

CCF Reaction

Pleochroism

None

Dispersion

Comments

Opal Doublet Chemistry & Crystallography

Chemical Name

Chemical Formula

SiO2-nH2O with base

Synthesis

assembled

Crystal System

NA

Classification

Nature

Composite

Crystallinity

Comments

Opal Doublet Characteristic Physical Properties

Hardness

Streak

Specific Gravity

Toughness

Inclusions

Look for assembled nature and glue layer in opal doublets. Look for straight separation planes to distinguish opal doublets from natural opal that contain a potch opal under layer. These stones might have areas of potch or matrix that lack play-of-color. Synthetic opal will have a more uniform play-of-color appearance. Stones are sometimes glued using black cement to give the appearance of a black opal.

Luster

Vitreous

Stability

Fracture

Cleavage

None

Comments

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