THE MATERIAL LIBRARY
Agate
Banded chalcedony, a fine-grained form of quartz.
Colors & patterns
Gray, cream, brown, red and other colors, often in curved bands.
Typical origins
Brazil, Uruguay, India and many other countries produce agate; each locality has distinctive varieties.
Hardness
6.5–7 on the Mohs scale.
Choosing & setting this material
A smooth dome reveals the banding beautifully. Bright, unusually uniform colors may be dyed; ask whether the material is natural-color or enhanced.
Care & cleaning
Clean gently with lukewarm water, a little mild soap and a soft cloth, then dry. Avoid steam, ultrasonic cleaners, harsh chemicals and sudden temperature changes, especially when treatments are unknown.
Origins above describe typical sources of the material, not the origin of an illustrated or stocked stone. Hardness measures scratch resistance, not resistance to breaking. Confirm the identity and treatments of the actual piece.
Further reading: Material reference · GIA: gem treatments