Here in the Western World, raku-style firing is different than the kiln firing processes that were passed down through families in Japan. Basically, by placing the red-hot fired piece in an aluminum container that allows carbon dioxide to pass through a small hole, you create a reduction chamber. This induces a reaction between oxygen and the clay minerals and metal elements of the glaze. By closing the container, after combustible materials in the can such as sawdust or paper, catch fire, the reaction pulls oxygen from the glazes and clay. Luster is created in the glaze because it's been deprived of oxygen. The matte black colour of raku pottery is achieved on pieces with no glaze, as the oxygen is pulled from the clay minerals.
"It is raku’s unpredictable results and intense color that attract modern potters. These patterns and color result from the harsh cooling process and the amount of oxygen that is allowed to reach the pottery. Depending on what effect the artist wants, the pottery is either instantly cooled in water, cooled slowly in the open air, or placed in a barrel filled with combustible material, such as newspaper, covered, and allowed to smoke. Water immediately cools the pottery, stopping the chemical reactions of the glaze and fixing the colors. The combustible material results in smoke, which stains the unglazed portions of the pottery black. The amount of oxygen that is allowed during the firing and cooling process affects the resulting color of the glaze and the amount of crackle.
"Unlike traditional Japanese raku, which is mainly hand built bowls of modest design, western raku tends to be vibrant in color, and comes in many shapes and sizes. Western raku can be anything from an elegant vase, to an eccentric abstract sculpture. Although some do hand build, most western potters use throwing wheels while creating their raku piece. Western culture has even created a new sub branch of raku called horse hair raku. These pieces are often white with squiggly black lines and smoke-like smudges. These effects are created by placing horse hair, feathers, or even sugar on the pottery as it is removed from the kiln and still extremely hot."
Ganoksin.com has a great overview on raku in jewllery-making.
There are a growing number of artists creating raku pieces for jewellers to use as components in their work. One of the best-known is Marianne Kasparian. She has an etsy shop, where you can check out her work. I suspect you'll recognize her signature hearts right away, since bead artists such as Sherry Serafini. This picture shows some of her small pieces that I've bead embroidered.
Duane Collins has an etsy page as well and I adore his small components, graceful birds, and squares in matte and luster finishes. I love the squares with holes for bead embroidered pendants but you can also just put a bail on the back of some pieces or string the bird on leather cord or chain.
Odd Designs sells at Bead and Button and has an interesting take on pendants to add into your jewellery creations. Urban Raku, another Bead and Button vendor, blings their raku pieces up with crystals.
Recently, I've been raku firing on copper using enamels. Basically I fire the piece until it's red hot then put it in an aluminum can and smother the burning paper. The unpredictability of the firing outcomes makes every piece an adventure.