Minerals make for very good inlay material and look very nice embedded in wood or metal. I inlay different minerals in several type of ring cores including stainless steel, tungsten, and rhodium plated. The materials come in different grades or granularity, most often sand-sized and powder. The powder packs a little more and so gives a more solid look. The sand, being granier, will look a little less solid, but it is still smooth and presents as polished.