Hmm. Interesting thread. I don’t make enamel bangles or rings. Those in the
photo more properly would be a process termed ‘Champleve’, rather than
Cloisonne. In Champleve, areas of metal are removed by acid, gravers or
possibly some combination. These ‘cells’ are then bordered by fairly thick
walls of solid metal that protect the edges of the vitreous enamels. In
general, that is how I’ve seen most of this style of making done. Yes, worn
frequently and none too gently the glass will get damaged over time. The
Balinese dancers done on silver rings come to mind. Many of the car badges,
key ring fobs, and all sorts of things were made like this in the past.
Still, they do hold up with some care for awhile. In Hawaii, name rings are
carved out in gold and the design is surrounded by black enamel. Again, the
enamel is protected by enclosing walls.School Class rings, some older style
rings… Cloisonne is most often done with wires within the design itself
and it can be combined into a Champleve piece, perhaps in addition with
granulation. Vitreous enamels were meant to simulate jewels, which have
always been costly and difficult to assemble. Enamel is certainly about
color and sparkle. Metals by themselves were grey or silver, gold colored
or copper hues. So other colors were made from stones and then glass and
eventually other substances.
I am very fond of vitreous (glass bearing) enamels myself, most fond of
transparent enamels that show the metals and engraving beneath the color,
or other line work. Deep colors capture my attention. Because vitreous
enamel is shiny and colorful, the term ‘enamel’ has been preempted to
describe everything from paint, to colored epoxy, to nail enamel, to make
that surface seem more unique. Ground glass specially formulated and
colored by oxides, vitreous enamel is bonded to metal (& a few other
surfaces) under high heat. Artistically, the surface does not have to
remain shiny, nor does it have to have transparency to be valid. The
history of enamel is centuries long, some museum pieces have had the metal
erode away, but the enamel portion remains.
On the web see: www.enamelistsociety.org There are guilds and societies
world wide, in the UK, the Netherlands, Georgia, etc. YouTube has some fine
tutorials on some of the processes involved. Jim Grahl’s Balboa Park
Carousel Egg is just drop your jaw gorgeous! Got some enamels on that! Whew!
Just my .05 cents for today 
Eileen Schneegas
Snow Goose Designs