Help restoring the colour in granite flooring

I have attempted to restore the Granite (http://tanbrown.org) floor of my kitchen, using diamond pads

The diamond pads have worked ok in removing the chips & scratches that the floor has acquired over the years

The problem is I cannot achieve the original deep dark black colour to the Tiles (http://www.g682.net)

I have spent many tens of hours buffing & polishing the Tiles (http://www.g682.net) , in an effort to restore the colour, unfortunately all in vain

I am guessing, a finishing compound may be required, to finish the Tiles (http://www.g682.net) correctly

This has been my 1 and (http://maplered.com) only experience, working with a natural Stone (http://g603.net) so any advice will be most gratefully received