Hematite also spelled as haematite, is the mineral form of iron (III) oxide (Fe2O3). It forms a complete solid solution at temperatures above 950 °C (1,740 °F). Hematite is a mineral, colored black to steel or silver-gray, brown to reddish brown, or red. Huge deposits of hematite are found in banded iron formations. Gray hematite is typically found in places that can have still standing water or mineral hot springs. Hematite can also occur without water, however, usually as the result of volcanic activity.
Black coating uses either ruthenium or TIN cobalt black to give a piece of jewelry a light black or completely black appearance. It is very durable and resistant to scratches. Black plating gives the jewelry piece a sense of masculinity and high-tech.