Our design team suggest you use Grout colour 43 Sand, as a subtle distressed grout line.
If you wish to bring out the brighter lighter tones, then Colour 20 Antique is perfect.
Recommended Grout Joints - (We have assumed that your substrate has a perfectly flat and plumb surface, please check with your tiler.)
4mm grout joint. Based on this joint size, 1 bag of grout would cover 6.7m².