Polishing opal & other stones

Today I was working on a carved piece of chrysoprase, polishing it
with cerium oxide on a dampened wooden dowel, and with a flexshaft.
Using magnification, I use 2.75X, I could clearly see a little cloud
racing across the stone, even 2 or 3 mm away from the area I was
polishing. The polish, by the way, with some serious work, is glass
smooth.

I don’t know what’s causing the cloud, but I suspect it’s some sort
of molecular change. It doesn’t require much pressure and the stone
doesn’t get very hot. ONe thing that also happens, after a while is
that the cerium disipates. I suspect the surface of the stone is
slightly removed and becomes the polish. I know that this can be
true with jade, at least with nephrite. That’s why heat is so
important with jade.

Try it for yourselves. It’s slick, No pun intended?

Derek Levin