Lapidary tumbling machines are filled with stones, grit and water
and can be either rotary or vibratory. While the machines are
identical to those used in jewelry finishing, the materials are crazy
different. Lapidary finishing requires having enough stone material,
whether scrap or cut goods to rub against each other and the grit to
finish. It is a science all in itself.
Probably the best current book on lapidary finishing comes from the
Harmon’s in Montana who are known for their exquisite cutting and
finishing of patterned Montana agate.
Now to the comment about magnetic finishing from Mr. Anderson - a
magnetic tumbler is loaded lightly with steel pins, water and a small
amount of jewelry. It is totally the wrong machine for finishing
stone. Like many tools we use, it has very specific things that it
should be used for, rocks isn’t one of them. It isn’t the end-all for
jewelry finishing either, but useful for some processes.
For learning about lapidary processes, go to one of the lapidary
discussion groups, you will get better advice on finishing stones
Author - Tumble Finishing for Handmade Jewelry.