NO. Do NOT use dark coloured grouts as they contain fine carbon pigment, which is very invasive and can cause staining. A popular choice which works well with many of our tiles is Davco Sanitized Colourgrout in a shade called Cashmere. Test your grout selection first on remnant or excess tiles, or a small area of the surface to ensure you are satisfied with the results.
The surface of the tile should be continually cleaned during the grouting process to prevent the grout from setting on the surface of the tiles.