J hoop: A hoop earring in which the hoop is elongated into a shape resembling the letter J rather than being circular.

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. There are two distinct mineral varieties that are similar in appearance but differ chemically - nephrite jade and jadeite. New Zealand Greenstone refers to nephrite Jade.

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.

Jargon: Registered trade name for a colorless, pale-yellow or smoky-brown variety of cubic zirconia from Ceylon.

Jasper: From the Hebrew word "yashpheh", meaning "glittering". 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. Jasper was once believed to have curative powers.

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.

Jewelry: Ornamental adornments worn on the body composed of precious metals set with real or imitation gemstones.

Job Lot: A collection of merchandise sold in one group for use in a specific display or fixture.

Jobber: An individual who buys job lots from manufacturers or wholesalers to sell for a specific display or fixture.

Jocla: A small string of beads at the bottom end of a necklace. The beads in the center of the jocla usually contrast with the beads surrounding it and may be larger than the beads surrounding it.

Jump Ring: A small oval or round wire ring used to link charms or pendants onto a chain. It is not usually soldered shut.