Small

• A small grout line width, about 1/16 inch, is possible if the marble flooring tile is consistent in size. Installing marble flooring with small grout lines decreases maintenance requirements and looks great; however, it may be more difficult to achieve as there is little "wiggle room" during installation. Unsanded grout is recommended for small joints up to 1/8 inch wide.
  
  

Medium

• Medium-sized grout line widths -- 1/8 to 1/4 inch -- require the use of sanded grout and are typically featured when moderate size variation occurs among the marble flooring or when tiles with cushioned edges are used. Because of a good trade-off between quality appearance and ease of workability, medium-sized grout lines are preferred by do-it-yourselfers and expert tile setters.
  
  

Large

• Marble flooring pieces that vary in size and shape require large grout joint widths -- 3/8 to 1/2 inch. Large grout joints necessitate the use of sanded grout. Marble flooring installed in different-sized, repeating patterns, such as the Versailles pattern, necessitates large grout line widths.