0.063'' Square Blackened Stainless Steel - 5/16'' Black Stainless RingsWe take our stainless steel rings and chemically process them to turn the surface layer to magnetite.The magnetite is a very dark grey color that is turned into a black by a dry oil. The rings will turn from black to dark gray after the oil wears off. Since the rings have an oil coating they are not 100% clean and this makes the anodized aluminum better for jewelry.Please note: Washing these rings will remove the oil layer that makes these rings a darker black. This can turn your rings grey or even back to a stainless color. This is not a quality defect.Also note: These rings can be polished to a nice hematite with a DRY tumble. DO NOT wet tumble as this is washing. DO NOT tumble agressively with steel shot as this is burnishing not tumbling.