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Damaged Opal

Hi! I have recently damaged an opal with a pumice wheel. I am not
knowledgeable in the least about polishing stones. What can I use ?
Thanks in advance!

Katie Harmon

Hi Katie, Not knowing the size and type of the opal or the type of
the setting makes it a bit difficult to offer advice, but here’s what
I’d do.

If it’s not severely damaged (I imagine the pumice wheel will just
have un-polished it??) and if the area of damage is not large you
maybe be able to touch it up without unsetting the stone.

Use 1,200 or 2,000 grit silicon carbide wet-or-dry paper glued to a
popsicle stick or similar to re-sand all over the damaged area until
you get a uniform satiny sheen. Do this wet. Carve the stick to the
shape you need. Then polish on a wet leather wheel with cerium oxide.

If it’s a larger area of damage unset the stone and do the same. If
it’s an evenly rounded stone you can glue the bottom of the stone to
the flat head of a long wood screw or something similar; hold this in
one hand, then cup your other hand with a pad of the silicon carbide
paper in it. Sand the stone this way, again doing it wet.

Then polish on a leather wheel (for just one stone you can rig up a
leather disc in the electric drill) using cerium oxide as a polishing
compound. Again keep it wet.

If it’s a boulder opal you’ll have more trouble, since you’ll need
to get into an uneven surface. Fine sand with silicon carbide
wet-or-dry paper on popsicle sticks cut to the shape you need. Be
careful to do it evenly and not to cut grooves. Then polish with a
small leather wheel, wet, with cerium oxide or similar, on the
foredom machine.

Hope that helps

Hans Durstling
Moncton, Canada