Sardonyx is a brown and white banded variety of onyx primarily used in glyptography.


Gemological Information for Sardonyx

Color: Brown and White Layers
Crystal Structure Hexagonal (trigonal)
Refractive Index: 1.535 to 1.539
Durability: Good
Hardness: 6.5 to 7
Similar Stones: Dyed Onyx
Treatments: Dyeing, Heating
Country of Origin: Brazil

Sardonyx Care

Ultrasonic Cleaning: Usually Safe (watch for glued together white and brown cameo imitiations)
Steam Cleaning: Usually Safe
Warm Soapy Water: Safe
Chemical Attack: Attacked by Hydrofluoric Acid and Nitric Acid may remove dye
Light Sensitivity: Stable
Heat Sensitivity: May Alter Color


  • Gem Reference Guide, Los Angeles: Gemological Institute of America, 1988. Pp. 45-48.
  • Newman, Harold. An Illustrated Dictionary of Jewelry, New York: Thames and Hudson, 1981. Pp. 269.
  • Schumann, Walter. Gemstones of the World, New York: Sterling Publishing, Co., 1977. Pp. 142.