1/8" grout lines. Being it is a small space.

Check with the manufacturer, but I believe you can have as little as 1/16" grout joint with natural stone tile. With stone, the thinner the joint the better. You'll need to use synthetic grout which takes some getting used to.

Thank you for your response! At what size would you use a 1/16 grout line?

Yes, I was told I can either use a 1/16 or a 1/8 with the tile we have.