Cliff -

Lee Valley sells diamond lapping film in a variety of grits.  The grits
they offer are 15, 3, 0.5 and 0.1 micron.  They aren't too dear and would
be a way to try those grits and see if they do the job for you without
selling your first born.

http://www.leevalley.com/us/wood/page.aspx?p=68943&cat=43072

Free shipping at the moment, too.

Phil