Different shades of brown or yellow are typically used for gel stains. The gel stain can be as light as white, or as dark as mahogany. Some gel stains also come in a bright red or a dark grey.
As of 2015, MyOldMasters.com offers a variety of gel stain colors from "pickling white" to "rich mahogany." Instructions on where and how to use gel stains are available on the site.
Gel stains are meant to be used on porous surfaces because the gel stain fills in small gaps that are present, forming a uniform and level layer on the surface.