Unless otherwise stated, our cubic zirconia and lab created gemstones/cabochons have been tested and found to be safe and stable when fired with fine silver metal clay - without using activated carbon.

Most cubic zirconia and lab gemstones can be safely fired in activated carbon. (Carbon is an adsorbent. Adsorb is a process where liquid or gas is not absorbed but forms on the surface) 

Firing metal clay safe gemstones in copper, bronze or sterling metal clay is simple but requires an extra precaution.  To protect the surface of metal clay safe gemstones, embedding base metal clay pieces in activated carbon during firing is strongly recommend. Include the chosen gemstone in your bronze, copper or sterling clay piece, dry, finish  - and then fire as usual, embedded in coconut activated carbon. 

The carbon adsorbs oxygen during firing and the lack of oxygen protects the stone from burning.  Gemstone marked as Carbon-Safe are oxygen-sensitive, but can be safely fired when protected by activated carbon.

Firing a Carbon-Safe Stone in Silver Clays. With this technique, you can safely fire most CZ’s and Lab gemstones in all forms of silver clay at the ideal temperature without sacrificing the stone or the integrity of the final product.

Please note: PMC OneFire 950 Sterling requires carbon firing only if a gemstone that you are embedding requires carbon firing.

Graphics and Colours should be used as a guide

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