I am new to this forum, so I hope I could hear from either a veteran or someone who has experience with this. I recently installed a carrara marble back splash. The tiles are 2" x 4" and they were glued to the meshing with a 3/8" space. My issue is, that I have read that unsanded grout should be used with polished marble so it won't get scratched, however, unsanded grout can not be used with grout lines greater than 1/8". So I don't know what to do in this situation, use unsanded so I don't risk scratching the tile but then it will crack later, or use sanded grout and scratch the brand new tile.
I also saw another Pre-mixed grout from HD called Simple Grout. This can be used with 3/8" grout lines and I don't believe it has sand. But this isn't real grout, so that is the downside there. Please help, I'm stuck!!