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Onyx

Quartz

By Tim Matthews, JD, FGA, GG, DGA,
CEO and President of JTV (retired)
Published: June 2014
Modified: September 2023
Onyx Polished
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Table of Contents
  • General Information
  • Onyx Colors
  • Alternate Names
  • Countries of Origin
  • History
  • Care
  • More About Onyx

Onyx is a variety of chalcedony that exhibits parallel bands of color, primarily black or white. Natural black onyx does exist, although it is rare. Most of the black onyx on the market has been treated using the sugar-acid method to produce the black color. Natural onyx has long been used for cameos and decorative objects.

General Information

  • Classification
  • Optical Properties
  • Characteristic Physical Properties
  • Chemistry & Crystallography
Common Name
Onyx
Species
Quartz
Transparency
Semitransparent - Translucent
Dispersion
Strength: None
Refractive Index
1.535-1.539
Birefringence
0.004
Optic Character
Uniaxial
Optic Sign
Positive
Polariscope Reaction
Aggregate (AGG)
Fluorescence
SWUV: Inert
LWUV: Inert
Pleochroism
None
Hardness
6.5-7
Streak
White
Specific Gravity
2.550-2.700 Typical:2.600
Toughness
Excellent
Inclusions
Onyx will have straight parallel layers of different colors.
Luster
Vitreous, Greasy
Stability
Good
Fracture
Conchoidal, Granular
Cleavage
None
Chemical Name
silicon dioxide (aka silica)
Chemical Formula
SiO2
Crystal System
Trigonal
Chemistry Classification
Silicate

Onyx Colors

  • Bi-color Onyx
    Bi-color
  • Black Onyx
    Black
  • Blue Onyx
    Blue
  • Brown Onyx
    Brown
  • Gray Onyx
    Gray
  • Green Onyx
    Green
  • Multi-color Onyx
    Multi-color
  • Orange Onyx
    Orange
  • Pink Onyx
    Pink
  • Purple Onyx
    Purple
  • Red Onyx
    Red
  • White Onyx
    White
  • Yellow Onyx
    Yellow

Alternate Names

True Onyx, Arabic Onyx

Countries of Origin

Uruguay; United States of America; Madagascar; Thailand; India; Canada; Pakistan; Unknown; China; Ireland; Brazil; Italy; Mexico; South Africa; Peru; Germany; Indonesia

History

Most black onyx is banded with white in its natural state. It is dyed to emphasize the banding or to eliminate the banding, based on the stone's intended use. Banded stones are ideal for cameos and carvings. Each creates a unique design and is never exactly like another. Onyx is a chalcedony. It's dyed in pleasing blue shades, crisp greens, bright pinks and even white. Primarily known for its deep black color, onyx is a favorite gemstone of jewelry professionals and consumers alike. Paired with summer whites, black onyx adds sophistication to any look.

Care

Much of the onyx sold today is dyed to enhance its color and to afford you years of enjoyment. As with all color-enhanced stones, clean with warm water and mild soap. Rinse thoroughly and dry with a soft cloth. Do not use chemicals, ultrasonic or steam cleaners.

More About Onyx

Somewhere around the mid-1500s, a noted mathematician and astrologer named Girolamo Cardona, wrote that, in India, onyx was used to cool love's ardor. Hmmm… Onyx is listed in the bible as one of the stones on the breastplate of judgement.Other cultures felt that onyx could be used to separate one from an unhappy or unhealthy relationship.Often worn as "mourning jewelry", some people believed that black onyx released sorrow and negative energy.As with all folklore, there is no science that confirms the folkloric attributes of onyx. We can confirm, however, that this shining stone is striking in the right setting and a must-have for any woman's jewelry collection.

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