PinMart's American Flag Patriotic Cloisonne Enamel Lapel Pin. Cloisonne is an ancient metal working technique developed centuries ago in China during the Ming dynasty. The craft is a multi-step enamel process used to produce jewelry, vases, and other decorative items. Also called hard enamel, cloisonne lapel pins are true jewelry grade products and are often viewed as collectibles. There simply is no higher quality lapel pin or greater perceived value then cloisonne hard enamel.