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#FiringCubicZirconia in metal clay is extremely popular, not only due to the historic popularity of the use of Diamonds in high value jewelry, but also because it is widely mentioned as "embed-able" with no specialized skills or tools required to create a prong setting required compared with traditional metal-work.

Most of what we will cover in this article will also apply to other so called "fire-able" gemstones, but before we dive in, it should be mentioned that my goal is to provide you with a compass to navigate the labyrinth of overly simplified information on this topic. To avoid the pitfalls when purchasing and creating with Cubic Zirconia. Also, to help you work safely.

So let's start with;

What is Cubic Zirconia?


 " (CZ) is the cubic crystalline form ofzirconium dioxide (ZrO2). The synthesized material is hard, optically flawless and usually colorless, but may be made in a variety of different colors. It should not be confused withzircon, which is azirconium silicate (ZrSiO4). It is sometimes erroneously called cubic zirconium. During synthesis zirconium oxide would naturally formmonocliniccrystals, its stable form under normal atmospheric conditions. A stabilizer is required for cubic crystals to form, and remain stable at ordinary temperatures; this may be typically eitheryttrium orcalcium oxide, the amount of stabilizer used depending on the many recipes of individual manufacturers. Therefore, the physical and optical properties of synthesized CZ vary. Cubic zirconia is relatively hard, 8–8.5 on theMohs scale— slightly harder than most semi-precious naturalgems. " - Wikipedia


Cutting through the chemical composition information, the key points to keep in mind;

  1. Pay attention and verify - Is that stone for sale Cubic Zirconia or Zircon? Avoid purchasing from any source who cannot explain the difference. CZ = Zirconium + Oxygen,whereas ZIRCON = Zirconium+Silica+Oxygen

  2. Color is an additive, this means a high level of variance when exposed to high heat. The results can include color change to cracking. Do not "expect" the same results when firing different color CZ.

  3. The level of stabilizer used in the fabrication ultimately will determine its tolerance to high temperatures....Not the price ;-)

Ultimately, the higher level of stabilizer, the higher temperature and the higher atmospheric pressure used in the fabrication is the real indicator of value. The higher production costs is the reasoning for the the higher price.


The result of a higher production temperature and atmospheric pressure is what creates a more dense gemstone. This results in a gemstone with a higher Mohs scale value. Although there is no assurance of sellers mislabeling their products, targeting higher Mohs scale value for your CZ can help avoid low quality gemstones. When successful, the higher value CZ also adds value to your creation.


ATTENTION: Low quality CZ can explode! Either during firing or if exposed to "thermal shock" by removing from the kiln while still hot. In fact all gemstones are susceptible to thermal shock, so ALWAYS let your kiln cool to room temperature before opening the kiln door.


Firing ANY gemstone, natural or synthetic comes with inherent risks. Rather than list these risks, you can measure your risk tolerance against the warnings contained in:


Cool Tools

click to view / download


One last tip if you opt to fire CZ in metal clay;

Always clean you CZ (or gemstone for that matter) with alcohol prior to firing!

The oils from your fingers or even dust can cause a milky film or small scratches to form on the surface during firing. View our post for a possible solution if you encounter this issue.


"CAN I fire CZ in metal clay?" = YES

"SHOULD I fire CZ in metal clay?" = That depends on your tolerance to inconsistent results and only if you are making an informed decision (that's the goal of #MetalClayAdventures).



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