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


Gemological information

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 Stabke
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.