There is another solution, not sure if you want to try it or not, but I'll just throw it out there anyway. I visited a friends world & he had stone flooring everywhere in his house, but instead of worrying about the gaps in the floor, he filled them with core wood log beams, so there is at least something in the ''small gap'' if you will. The core wood logs beams are rounded & hence they sort of protrude *slightly* at the top of the seam in the floor, gives it a decent look too.