There are three primary types of stain that you can use. Acid-based stains provide the most natural look, and penetrate deep into the concrete to provide a strong, long-lasting look. Solvent-based stains provide a more vibrant look, though they do not last as long as acid-based stains. There are also eco-friendly stains available, such as "SoyCrete," which are acid-free and non-toxic, but cost much more than the other two options. As for color, acid-based stains are limited in options and primarily show earthy tones, whereas solvent-based stains provide a wide variety of colors to choose from. Also, acid-based stains create a more varied consistency due to the natural lay of the rock, whereas solvent-based stains have more consistent color.