Vintage Hematite (aka Black Diamond) with Pearl Navajo Sterling Silver Ring Available in Sizes: 5,7,8,9&10 Artist Signed Initial marked: CH Hematite: the black diamond| Hematite is a compact form of iron oxide that can be found in varying degrees of hardness, each with different appearances and uses. Some other names for the gem include bloodstone, iron rose, kidney ore, martite, paint ore, specularite (specular hematite), rainbow hematite and titano-hematite