J

Japanese twin

Form of contact twinning where two single Quartz crystals are joined by the their base at an angle near 90°.

Jet

Coal that can be polished and used for ornamental purposes.

Jewel

A gem, whether cut or uncut, capable of being used as an ornament.

Jeweler

Individual whose trade is to buy and sell jewels and gemstones.

Jewelry

Jewels worn as ornaments.