Enameling in jewelry is basically the application of glass power which is then fused by heat to make a smooth, shiny, colored field or line on the piece. There are many different styles of enamel work. Three of the more common ones seen in antique European jewelry are:
Guilloche: (gee-oh-shay) Transparent or translucent enamel is placed over metal that has often been enhanced with a pattern. The technique is commonly named "engine turned" for the mechanical cutting of lines on metal to create a design. Light reflects through the transparent enamel, highlighting the engraved pattern.
Champleve: Channels are carved out of metal to make a well which is then filled with enamel. The partitions are part of the base and not applied on the surface. French for “raised field” or “raised plain.”.
Plique a jour: Aftern enameling, the metal backing is removed, leaving a delicate, translucent design that resembles stained glass.