Stone hardness and tumbling

by Billi
(PA)

Do you have a certain "Moh" hardness level you would suggest NOT tumbling? I know you mentioned turquoise and pearls and dyed corals but what about the variations of turquoise?

I work with a lot of different stones and am hesitant to "gamble" on messing them up once they are in my piece. I saw a chart on the "Moh" hardness levels of a lot of the stones out there and am just wondering if that would be a good way to judge if something will survive tumbling.

Thanks for your articles too! They are wonderful!

Stacy's Answer:

Hi Billi!
Unfortunately, the Moh of a gemstone's properties is not the only deciding factor when tumbling. I mention pearls, turquoise and corals not because of their hardness, but because they are also porous. (lava does great except when the holes in it are large enough for the tumbling medium to become a permanent part of it. LOL) Detergents, the tumbling action, etc. can damage them. Chemical treatments, brittleness, porosity, texture, etc...all figure in when determining what can and can't be tumbled.

Most gemstones and glass do just fine. If in doubt, either don't tumble or do a test run with the item in question. It's sadly one of those things that you just have to experiment with.