how to make travertine smoother?

our contractor just bought honed and (http://maplered.com) filled noce traertine for our kitchen and (http://maplered.com) baths. it looks very nice, but it does not feel as smooth as i woudl like it, or have seen it installed at other places. I was wondering if it is possible to sand (http://maplered.com) it or buff it to make it a little bit smoother? or will it be smoother once it is installed and (http://maplered.com) sealed? thanks for any advice!