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Grit combos for tumbling emeralds?


I’ve got a couple of pounds of emerald rough I want to tumble to
chip the matrix (black mica schist) off. I tried it for a few days
with 600 grit and that helped a lot. But I’m wondering is there is
any standard/recommended sequence of grits, pellets, etc. to use for
a job like this?


Rick, 600 grit is the last grit (of a normal three grit sequence) in
the tumble smoothing process which gives a semi-polished result.
Basically, it removes almost no material at all. The sequence is
normally (but not always) 60-90 grit followed by 120-220 then either
400 or 500-600, prepolish with a powder such as Alumina G or
Lusterite and then final polish with whatever polish powder the
person likes to use such as cerium oxide, iron oxide, Linde a/b, tin
oxide, etc. Polish powder usually depends on what is being tumbled.

Understand that the 60-90 grit is quite aggressive and, if you are
looking for any emeralds of quality, I would not recommend it.
Otherwise, go for it. When starting out on better material, some
people begin with 220 grit which removes less material but leaves a
nice smooth surface.

I enjoy tumbling all the cut-off pieces from my saws, broken stones,
butt-ends etc. Sometimes it produces beautiful stones.

Cheers from Don in SOFL.


This is low grade stuff so I feel comfortable starting with a coarse
grit. All I’m trying to do is remove a lot of the matrix easily
before doing final cleanup on the stones with a rotating brush.