The gemstone called hematite is an opaque stone that polishes to a semi-reflective silvery black, most commonly carved into beads or rings, but sometimes faceted. It's often seen in combination with onyx which has been dyed to become flat black. As hematite is an iron ore, large stones are quite heavy to wear, but attractive. (Plastic or lighter metal substitutes are not uncommon either.)

The reddish version of the same mineral is not often worn as jewelry; the name bloodstone encompassed both this red hematite and a type of chalcedony.