Pfaltzgraff makes something to remove knife marks from their plates.....but I have a hunch that silver polish would do the job.
Linda C

Ah, interesting! I'll try it. Thanks very much, linda.. I had a feeling you'd know this one. :)

Just tried it (Flitz, actually) and it got them out, for the most part--thanks so much. Maybe if I use real silver polish they'll come all the way out. The jar gets to stay :)

Aluminum is notorious for marking ceramics and stomeware. The mark welds itself to the ceramic and it is almost impossible to remove. However, the mark does not penetrate the ceramic and is on the surface so there is a chance that vigouous scrubbing can remove most of it. The problem is that such scrubbibg may also scratch the finish of the ceramic and make a mess of it. Use scrubbers and abrasives that are softer than the surface being rubbed.

The problem is compounded in that the mark is largely aluminum-oxide, a gray color, and is resistant to many chemicals. The solution: Keep aluminum away from your good china, etc. Be careful about laying aluminum pots and pans on ceramics when washing the dishes. Better yet, do not wash aluminum with the ceramics.

Interesting....I have a ceramic tile counter top around the cooking appliances....and have laid many an aluminum pan on the surface and never left any sort of a mark, I regularly wrap bread and rolls in aluminum foil and it never leaves a mark...
I do know that matte finish stoneware may be marked with stainless steel knives, but have never had any marks on porcelain and I use porcelain china every day.
Linda C