Enameling is the process of fusing powdered glass to metal at approximately 1500 degrees Fahrenheit. There are many different processes within the medium of enamel. Here are some processes with images to help.
Champlevé is the process of filling in recessed areas to create a flat surface. The enamel is carefully added to the piece, fired, and sanded down to make the piece nice and flat. This style dates back to the Byzantine era.
Basse-taille is the process of creating recessed areas through etching, filling those areas, and using beautiful transparent enamel on top.
Cloisonne is a time-consuming process of bending and twisting fine silver or 24k wire to create imagery. Each space within the walls of the wire is filled and sanded down to create a beautiful image.
Enamel Decals are my favorite. Found imagery is scanned, photoshopped, and printed on decal paper. The image is then transferred to the enamel and fired in a kiln.
Painted Enamel is the process of adding color by use of either powdered pigments and oil or enamel watercolors.
These "scribble earrings" are another example of the "painted" look.
Etching is the process of creating a resist on silver, copper, or brass. The metal is then placed in an acid bath. The exposed areas are then etched creating a depth of the image in the piece.
Keum Boo is a process of fusing 24k gold to fine silver by way of heat.