7 millimeters (7mm) of smooth black zirconium. This one features all high polish with satin finished middle, and step edges. Black Zirconium has quickly become a popular metal for wedding rings. Our Zirconium is very hard and durable, zirconium stand the test of wear. The zirconium metal begins as bright silver metal. We then use a slow, controlled process of intense heat to produce this permanent black metal. Once the black zirconium is polished, heated and cooled, we can mill grooves and patterns (if applicable) that gleam in the silver zirconium color. We can make this wedding ring for you in a variety of widths. **PLEASE READ** No Returns / No exchange. Lashbrook DOES DO NOT SIZE-EXCHANGE. Please research your ring size with comfort-fit sizing gauge.