Alan - You are on to something - only don't use steel for this.
First - oxidize your pieces.
Second - Put them in a medium abrasive and run in a vibratory
tumbler for about 6 hours.
Third - Remove, set stones and sell.
Couldn't be easier, works every time.
If you only have a rotary tumbler, you can double the time, and
check to see when it's done. Usually takes 2 to 3 times the vibe.
In either case, be sure to use appropriate chemistry for the media.
I agree with the last post on tumblers - if you only can have one,
get a good vibratory tumbler. My tumbler is my favorite employee -
no vacations, sick leave or Monday morning brown bottle flu.