Tom Watson wrote...
I wonder if there is any kind of treatment that would render the
pieces more resistant to this kind of damage without substantially
altering the look.

Not that I know of. Ebony is so dense that liquids don't penetrate into
it very well. I should temper that a bit; I've only worked with Gaboon
ebony, but the ebony chess sets I've played seemed very much the same.

I remember back when lots of folks were using PEG
(PolyEthyleneGlycol)(sp?) to stabilize wood - not for this purpose but
the basic idea of an immersion in something that would alter the
characteristics of the wood is what I'm going at.

There might be something to that. I've tried to look into wood
stabilizing some, and have been unable to find anything definitive. One
of those "industry secret" things. (BTW, I *hate* that!) However, I have
noted that the stabilized materials -- especially burls -- that I've seen
have had a "plasticky" appearance and feel, almost like it was
impregnated under pressure (or vacuum?) with something like epoxy. It
would be nice to know more about the processes available, and whether any
leave a more natural appearance to the surface, which is my personal
preference.

Good luck!

Jim