On Wed, 31 Aug 2005 16:55:05 -0500, Richard J Kinch wrote:

If you inspect it closely with glaring reflected light,
you should see the original polished surface quality, as opposed to
dullness from misuse or abuse.

That is a really, really good point. Polish, if intact, tells you that
the flatness is still intact. Oversimplified, but probably an excellent
measure of the "health" of the stone.