It's a finish that we selected for our client and was then customized by a specialty flooring company. In this case, it's a polyurethane with a satin finish (not high-gloss) for a near-matte look. It can also be achieved using an oil-based product. The grey-silver coloring is not only created by the stain. It's also created by treating and curing the wood (it's triple fumed) before staining. It's definitely a professional job if you want to obtain depth and dimension in the flooring! The wood is European Oak and the stain product is from Belgium. A retail product that offers a wide range of rich floor finishes is Hakwood.