Black Opal

saf-ahyuh r
October Birthstone

Black opal is the rarest and most valuable variety of opal. Black opal displays “play of color” and has a black, gray, dark green, dark blue, or blackish brown body color. Most black opal comes from Lightning Ridge and Mintabie, Australia, but it can also be found in Java, Virgin Valley, Nevada, and Wello, Ethiopia.

Black Opal Polished
Black Opal Classification
Common Name Black Opal
Species Opal
Black Opal Optical Properties
Transparency Opaque-Translucent
Dispersion Strength: Weak Fire
Refractive Index 1.370-1.470
Optic Character NA
Optic Sign NA
Polariscope Reaction Anomalous Double Refraction (ADR), Singly Refractive (SR)
Fluorescence SWUV: Inert, white, light blue, green and yellow
LWUV: Inert, white, light blue, green and yellow
CCF Reaction None
Black Opal Characteristic Physical Properties
Hardness 5.5-6
Streak White
Specific Gravity 1.250-2.30
Toughness Varies
Luster Vitreous, Resinous, Dull, Waxy
Stability Poor
Fracture conchoidal
Cleavage none
Black Opal Chemistry & Crystallography
Chemical Name hydrated silicon dioxide
Chemical Formula SiO2*nH2O
Crystal System NA
Chemistry Classification Silicate

Black Opal Colors

  • Bi-color Black Opal Bi-color
  • Multi-color Black Opal Multi-color
  • Gray Black Opal Gray
  • Brown Black Opal Brown
  • Black Black Opal Black

Countries of Origin

United States of America (the); Honduras; Australia; Peru; Ethiopia


Avoid heat, chemicals, ultrasonic, and repolishing.

Sisk Gemology Reference

Showcasing 200 gemstones in over 1,000 pages and accompanied by more than 2,000 photos, The Sisk Gemology Reference is a must-have in every collector’s library. Each comprehensive, three-volume set features state-of-the-art photography, detailed illustrations, and scientifically precise descriptions to create an entrancing experience for gemstone amateurs and afficionados alike.

Shop Now

Tim Matthews


Tim Matthews

Tim Matthews is President and Chief Executive Officer of Jewelry Television® (JTV), as well as a member of the company's Board of Directors. He oversees and leads all aspects of the company's powerful omni-digital retail platform that uniquely specializes in fine jewelry and gemstones. His passion for business and gemstones has led him to become a recognized expert in the field of gemology. He is a life member of the Gemmological Association of Great Britain (Gem-A) and has earned Gem-A's highest degrees, the Gemmology (FGA) and Diamond (DGA) diplomas. He is also a Graduate Gemologist (GG) of the Gemological Institute of America (GIA) and has also completed GIA's Graduate Diplomas in Diamonds, Colored Stones and Pearls. Under his leadership, JTV has become the leader in the sourcing and selling of color gemstones and jewelry.

This page was created on June 27, 2014.

This page was last edited on October 24, 2019.