Stones add interest to jewelry, and open up many design possibilities. They can just be focal points of color, or they can be part of a design. However, stone setting for the metal clay artist and stone setting for the metalsmith are different. I’m going to discuss a few of the ways metal clay artists can set stones.
First of all, fired metal clay and sheet metal are different. They might look alike, but they are different at a molecular level. Sheet metal has long chains of molecules. Metal clay has very short ones. Accordingly, sheet metal can bend a great deal. Metal clay can bend a little. However, if you bend it too far, it is likely to break. That means that some methods of stone setting, such as the use of tabs, that are available to the sheet metal worker are (almost) impractical for the metal clay artist.
Directly Setting the Stone in Metal Clay. The short version — be cautious about what stones you put in your kiln. Some will, simply, be destroyed from the heat — actually, most. Some will discolor — an example is moonstone, which can emerge just fine, or can emerge from the kiln a dull gray. Be careful of published lists of stones that can be fired — many mean ‘will not be destroyed, but still could emerge discolored’.
Some stones that I have directly fired and have had good results with: synthetic ruby; synthetic emerald; natural sapphires; and diorite.
Most cubic zirconia will fire safely. However, some colors are heat sensitive, and must be low fired. Most manufacturers of cubic zirconia recognize the metal clay market, and tell you how heat resistant the stones are.
In any case, when you set a stone directly in metal clay, you must remember that metal clay shrinks. If the stone has nothing to hold it in place, it can be spit out like a watermelon seed.
Also, if there is any metal clay dust whatsoever on the stone when it is fired, the dust will adhere to the stone, turning it cloudy. Once it is fired, the cloudiness is impossible to remove. However, the dust can be removed, pre-firing, using a cotton swab and denatured alcohol. Just be sure you get every last drop of the dust!
The other options listed below require you to set the stone after the metal clay has fired. This has the advantage that you can use any stone you like. For example, the stones in the photograph above are vesuvianite. Vesuvianite will not fire. However, it can be incorporated post-firing.
Prongs. Prong settings that can be directly fired with metal clay are commercially available. Follow package directions, and things will generally work. However, most of these settings are not strong enough for rings. That means, as a metal clay artist, you will be limited to jewelry that will take less stress than rings.
Wire settings. It is possible to embed jewelry grade wire in metal clay (warning: if you use copper, be sure it is jewelry grade, not from the hardware store) (second warning: be very careful about mixing fine silver and sterling silver — sometimes it works and sometimes it doesn’t). If you make sure that the wire is bent over so it has ‘feet’ for the metal clay to grab onto as it shrinks, you can firmly attach the wire. The wire can then be bent over stones to produce a sort of wire-wrapping.
Bezel wire. Bezel wire is flat wide wire used to make bezels. Some of it has prongs, or ‘feet’, that prevent the metal clay from shrinking out of shape. Some does not. If you use the prong type bezel wire, you need only form a bezel of the size and shape of your stone. If you use the other type, you must calculate and account for shrinkage. This might be your only option with an irregularly shaped stone.
Note that bezel wire must be bent to firmly grasp the stone. This is quite easy, if you use a metal burnisher.
Bezel cup. Bezel cups are cups, of the same metal as the clay, that are of the size of the stone to be fired. Like bezel wire, the edge of the cup must be bent to grasp the stone. Like bezel wire, this is easy with a metal burnisher.