water rings and spots

I have an absolute black tiled counter top that gets water rings and spots very quickly.  The tile has a good amount of silver flake in it.  I don't know if this helps identify it or not (since there is no such thing as black granite).  The contractor put an impregnator on it after installation and I have had nothing but trouble since.  Is there a fix for the spots and rings or am I just going to have to stop using my counters?  Thanks Reed