Polishing rough stones: Jasper, Agate and Aventurine

Hello everyone, Meg here.

I have been frustrated over and over with trying to polish purchased stones from local shops and getting mixed results. Mainly because I was clueless with the process.

So I decided to venture out there and do some reading. I found out there is a thing called Mohs scale of mineral hardness.

If you’re like me, you have this deer in the headlights look.

Without giving you the master’s thesis on the subject, plain and simple you want to polish stones with similar hardness based on the mohs scale








(courtesy of Natural Park Service).

If the batch has different hardness, the stones will polish at different rates or times, thus the mixed results.

You could possibly be damaging or preventing the best results for each stone.

OK, now armed with more information and following the Kingsley North, Inc. rock polishing instructions KingsleyNorthInc,

I’m on a mission to conquer rock polishing. Arrrrrrggggghhhhh! Whatever tribal yell you wish to use.

I’m starting with rough stones purchased from the Gem Shop and Hayneedle. You may choose whoever.

The important step is matching hardness.











1 lb – Kambaba Jasper – 6.5 MOH

1 lb – Jafar Jasper – 7 MOH

1 lb – Yellow Aventurine – 7 MOH








1 lb – Botswana Agate 6.5 – 7 MOH


I have a Mini-Soni MT-10SV Dual Vibratory Rock Tumbler 2 – 4 lb capacity hoppers.

This does make noise and you should be prepared to deal with the vibration and hum sound that is produced when the machine is running.

Kaz built a sound/vibration dampening box out of cinder blocks and 1” foam insulation.

It works well, but we still have a faint humming sound coming from our garage.

Plus I think we have adjusted to the noise.







Polishing Powder

Silicon Carbide 70/90 blend, 120/220 blend, 600

Ceramic media

Plastic pellets












I completed step one by using 60 grit and running it in the tumbler for 24 hours over 7 days and then washing/rising for another 24 hours.

The results were rounded and smooth edges.







Jafar Agates and Yellow Aventurine


Step 2 I ran for 24 hours over 5 days using the 120/220 grit. I couldn’t wait any longer. Did I mention I can get a bit impatient, LOL.

Now I have a matte or dull looking finish on the stone.

20160704_111404 20160704_114813










It’s right in line with the instructions. So far so good, but still many ways to mess it up, but I’m taking an optimist view and I’m confident that these will be something that Indiana Jones would be hunting down.

Well, maybe something really pretty.

I’ve got the stones back in the machine for about 5 days and we’ll see what we get.

See ya later