Gems & Gemology
Fall 1981, Vol. 17, No. 3

Heat Treating Ruby and Sapphire: Technical Aspects

Peer Reviewed Article
Kurt Nassau
Ruby and sapphire of natural or synthetic origin can be heat treated to improve asterism; to remove asterism or silk; to improve, add, or remove color; and even to alter imperfections. At least nine distinct processes can be identified, although several may occur simultaneously. Some of these treatment methods correspond to natural processes and may not leave any evidence of their use; others do not correspond to natural processes and are readily identifiable.

Get the latest
Gems & Gemology

The quarterly journal of the Gemological Institute of America.
 
Download the
Fall 2013 issue

GIA On Location

Field reports, videos, photography, and firsthand accounts from mines and industry hot spots around the world.
 

Learn More About Ruby

Why We Love
Explore ruby history, research, quality factors, and more in the GIA Gem Encyclopedia.
 
Read More

Learn More About Sapphire

Why We Love
Explore sapphire history, research, quality factors, and more in the GIA Gem Encyclopedia.
 
Read More

You Might Also Like

Resources For Retailers
learn more
Shop the Campus Store
Learn More
Exhibit: Starry Night Sapphire
Learn More
G&G Winter 2013 Edition
Learn more