Lemon Juice Test

Hi,

I told my contractor to install my carrera marble flooring without any grout lines and when I went over to check on the job there were ¼ inch grout lines.  I am concerned that when the sanded grout is placed between the stones, and they seal it, the sanded grout will scratch the polished marble surface.  Is the anything I can do about this?

Arlin Crane