Jabot Pin: A "jabot", (pronounced zhah-Bow), is a kind of ruffle worn on the bosom of a man's shirt or woman's blouse. The jabot pin was designed to hold the jabot onto the shirt. It is basically a pin with a brooch at either end. One brooch is removable so that the pin can be stuck through the garment and then secured by reattaching the removable brooch. It is a form of Art Deco mourning jewelry.
Jade: An opaque semiprecious gemstone which is usually found in shades of green, but can be also be found in lavender and rose shades.It's a traditional stone in China where it has been mined since 6000 BCE.
Jadeite: A hard, translucent variety of jade which is rarer than the other varieties of nephrite and comes in a variety of colors such as orange, pink, yellow, brown, blue, violet, and black.
Jasper is an opaque, impure, cryptocrystalline variety of quartz that may be red, yellow, or brown. It breaks with a smooth surface and can be highly polished like marble. Varieties of jasper include Fancy Jasper, Picture Jasper, Poppy Jasper, Red Jasper, and Striped (or Banded) Jasper.
Jet (also called "black amber"): A dense black variety of lignite (fossilized coal) that can be highly polished and is often made into mourning jewelry, Zuni inlay, toys, buttons, etc.
Japanned: Metal that has been enameled black or charcoal gray
Jump Ring: A small oval or round wire ring that can be opened to link charms or pendants onto a chain.