2 part question Gemstone and Tumbler Size?
September 26, 2008
I cut, polish and wrap stones and have a 12lb tumbler. You talked about tumbling pearls... Do you know about tumbling precious & semi precious gemstones and/or a good place to get that kind of information?










I don't know of a single "clearing house" for that kind of information, but I can offer some ideas. First of all, if the Mohs hardness (diamond is 10, talc is 1, your fingernail is 2) of a particular stone is very low (perhaps 3 or less??), then it is unlikely to handle tumbling. These stones may also be difficult to wrap for the same reason. If you have a small sample of the same type of stone, perhaps as a bead, then you could simply test it in the tumbler. Try googling "gemstone hardness" and you will find a number of sites to explore.
When in doubt, you could negate much of the need to tumble your work by cleaning and pre-polishing the wire before you use it to wrap your stones. Finish by scrubbing with Dawn and a toothbrush, and a final hand-polish with a polishing cloth.
The stones I have successfully tumbled so far: freshwater pearls, stabilized turquoise, jasper, amethyst, serpentine, dyed coral, onyx, obsidian, malachite, lapis lazuli, sodalite, peridot, garnet, and some more I am forgetting.
The only "stone" I am unwilling to put in the tumbler is amber.
I am not sure of all the stones you CAN tumble, but I do know of three that you CANNOT, or at least, should take care when you do: pearls (they tend to get dull), turquoise and apatite (they are too soft or brittle.
I have learned NOT to tumble any stones lower than 4 or 5 on the MOHS scale. I find it much better to stabilize and use the grinder/polishing machine to shine up those stones. I have successfully tumbled the softer stones in my vibratory tumbler a couple of times, so if you want to try tumbling soft stuff that would be the only way I'd do it. If your stones are quite valuable, I wouldn't risk them in any tumbler.
I have a tutorial coming out this week (as long as the gremlins leave my typing fingers alone). I'll have a couple of suggestions of good resources as well.