Firing Gemstones and Natural Stones in Art Clay® Provided by Art Clay® World
This chart provides information on the gemstones and natural stones that can be safely fired with Art Clay and which stones should be avoided. Use the following key to determine what stones are safe to use with the Art Clay products available:
** - can be safely fired in place with Art Clay Silver Standard and Slow Dry Formula, in addition to all 650 Series.
(650) - can only be fired with Art Clay Silver 650 Low Fire Series.
| Elected Gemstone Characteristics | |||||
| Stone | Hardness (Mohs) | Specific Gravity | Refractive Index | Dispersion | Durability |
| Alabaster | 2-2.4 | 2.2-2.4 | 1.52 | med-high | low |
| Alexandrite** | 8 | 3.68-3.79 | 1.54-1.75 | low | high |
| Amber | 2.5 | 1.03-1.10 | 1.54 | none | low |
| Apatite (650) | 5 | 3.16-3.22 | 1.64-1.65 | low | medium |
| Aquamarine | 7.75 | 2.68-2.70 | 1.57-1.58 | low | high |
| Azurite | 3.5 | 3.8 | 1.48-1.65 | none | low |
| Beryl (650) | 7.75 | 2.68-2.70 | 1.57-1.58 | low | high |
| Cat's Eye** | 8 | 3.68-3.79 | 1.54-1.75 | low | high |
| Chalcedony | 7 | 2.65 | 1.55 | low | high |
| Chrysoberyl** | 8 | 3.68-3.79 | 1.54-1.75 | low | high |
| Corundum** | 9 | 3.95-4.10 | 1.762-1.770 | low | high |
| Diamond | 10 | 3.52 | 2.42 | high | high |
| Emerald** | 7.75 | 2.66-2.70 | 1.57-1.58 | low | high |
| Epidote | 6 | 3.25-3.49 | 1.73-1.76 | med-high | high |
| Feldspar | 6-6.5 | 2.54-2.58 | 1.522-1.530 | low | medium |
| Garnet (650) | 7.5 | 3.70-4.16 | 1.74-1.89 | med-high | high |
| Gypsum | 1-1.5 | 2.3 | 1.53 | med-high | low |
| Hematite (650) | 5.5-6.5 | 4.95-5.30 | 2.94-3.22 | none | high |
| Jade / Jadeite | 6.5-7 | 3.30-3.38 | 1.66-1.68 | none | high |
| Jet | 3.5 | 1.1-1.4 | 1.64-1.68 | none | low |
| Kunzite | 6.5-7 | 3.18 | 1.660-1.676 | medium | low |
| Labradorite (650) | 6 | 2.70-2.72 | 1.55-1.57 | medium | medium |
| Lapis Lazuli | 5 | 2.76-2.94 | 1.5 | none | medium |
| Malachite | 3.5-4 | 3.25-4.10 | 1.655-1.909 | none | low |
| Marble | 3 | 2.71 | 1.48-1.65 | none | low |
| Moonstone (650) | 6 | 2.58 | 1.518-1.526 | low | high |
| Nephrite | 6.5 | 2.96 | 1.62 | none | high |
| Obsidian (650) | 6 | 2.33-2.60 | 1.48-1.51 | high | medium |
| Olivine | 6.5-7 | 3.3-3.5 | 1.654-1.690 | medium | high |
| Opal | 6 | 1.97-2.20 | 1.45 | none | low |
| Peridot (650) | 6.5-7 | 3.3-3.5 | 1.654-1.690 | low | medium |
| Quartz | 7 | 2.65 | 1.55 | low | high |
| Rhodonite | 5 | 3.53 | 1.73-1.74 | none | medium |
| Ruby** | 9 | 3.95-4.10 | 1.762-1.770 | low | high |
| Sapphire** | 9 | 3.95-4.10 | 1.762-1.770 | low | high |
| Serpentine | 3.5 | 2.5-2.7 | 1.57 | low | low |
| Sodalite | 5 | 2.13-2.29 | 1.483 | low | medium |
| Spectrolite (650) | 6 | 2.70-2.72 | 1.55-1.57 | low | medium |
| Sphene | 5-5.5 | 3.52 | 1.95-2.05 | high | medium |
| Spinel** | 8 | 3.6 | 1.72 | low | high |
| Spodumene | 6.5-7 | 3.18 | 1.660-1.676 | low | low |
| Steatite (soapstone) | 1-1.5 | 2.7-2.8 | 1.540-1.590 | none | low |
| Topaz (heat diff.)** | 8 | 3.54 | 1.63 | low | medium |
| Tourmaline | 7 | 3.06 | 1.63 | low | high |
| Turquoise | 5 | 2.6-2.8 | 1.61-1.65 | none | medium |
| Zircon | 7 | 4.02 | 1.81 | high | high |
|
Warning: Do not subject stones with fractures or heavy inclusions to direct heat (such as a torch or kiln). This could cause the stone to explode. Fire Mountain Gems cannot be responsible for stone breakage or accidents resulting from firing gemstones. |
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