Many natural gemstones can be set into metal clay and fired in place. Other Red Agate gemstones will not survive the heat of a kiln and should be set after firing. The charts below show the results of kiln and torch tests that have been performed on both natural and synthetic gemstones, adapted with permission from the original testing by Kevin Whitmore of Rio Grande, with additional testing by Cool Tools.

This information is for reference and should be used as a guide. There is always some risk of losing a natural agate jewelry gemstone even if others of it’s kind have survived in the past. Gemstones may have internal flaws that can be liquid or gaseous filled, or contain crystals of other materials that can cause the gemstone to fail where it usually does not. This guide aims to help metal clay artists sort out gemstones that are known to survive under fire from those that are not.

Gemstones are minerals that are classified into groups based upon the constanc ... Read more »