Lots of people have heard of cloisonne; this technique is a related one called champleve. The difference is that the walls of each color section are formed differently. In cloisonne the walls are built up or added in, for champleve I create the walls by etching into a solid piece of metal until each section is the proper depth.
I mix my own colors and add them in drop by drop using a toothpick, adding patina to create age and depth. I love the vibrancy of the colors and especially the sense that I'm wearing a miniature portrait.