Back to Ganoksin | FAQ | Contact

Re-finishing the surface of the opal


#1

I have a ring set with a flat top boulder opal. Over the years the
opal has become scratched. Is there a way that I can re-finish the
surface of the opal, easily and gently w/wo removing it from the
bezel setting. Thanks, in advance, for all help.

Linda


#2

Linda, the answer depends on the opal, and the bezel. Generally,
you will not be able to get a good polish near the bezel. If the
stone is set like an inlay, and you can remove some metal in the
process of re-cutting and polishing the opal, then you have an easy
task. However, if removing any of the metal will damage the
structure of the setting, then you must remove the stone before
trying to polish it. A check here is to lay a straight edge across
the stone and the bezel. If there is any light showing at the
junction, you will have a re-polish problem, and the stone should be
removed to re-polish it. If you have a border that has a continuous
surface between the opal and the metal, then you can sand out the
scratches and then polish out the stone and the metal. Sand out the
scratches using a 600 grit wheel with a lot of water. when the
scratches are gone. then polish out the stone and the metal on a
leather disk with Linde-A. Keep it very wet and polish out the
stone quickly. After the stone is polished, the metal will need
only a quick touch with rouge to finish it.

To remove the stone, a common jack knife is one of the best tools.
Work at the bezel and apply pressure away from the stone, IE pull
the metal away, don’t try to pry it away using the stone as a
fulcrum. Any pressure on the stone will fracture it. A boulder or
doublet is especially prone to damage here. Once the bezel is
pulled back, it is time to see if the stone was set in epoxy or
other adhesive. Also it is important at this point to determine if
the stone is a boulder or a doublet. If it is a boulder, a bath
over night in MEK or Attack is in order to make sure there is no
adhesive to inhibit the removal of the stone from the setting. If
you suspect that the stone is a doublet, you have a problem. The
MEK or Attack will also attack the bond between the opal and the
backing of the doublet. If the surface of the stone is very flat,
then it is most likely to be a doublet. It it is very uneven, It is
most likely to be a boulder solid. It is the grey area that causes
the problem.

In any case, once the opal is removed, the standard re-cut,
re-polish techniques can be used. Just be very careful when
resetting the stone to have minimal polishing left to do near the
stone or you could be back in a viscous loop of damaging the stone
while polishing the metal and trying to correct the damage.

Don


#3
Is there a way that I can re-finish the surface of the opal, easily
and gently w/wo removing it from the bezel setting. Thanks, in
advance, for all help. 

Very carefully, and slowly. An experienced lapidary could probably
do it fairly easily. You can think about it much in the same way as
if you were trying to remove a scratch from metal. It involves
abrading (grinding down) the surface until the scratch is removed,
then sanding with successively finer grits until a fine surface is
achieved. Then a final polish is applied with a polishing compound…
in this case cerium oxide on leather is a good choice.

If you don’t have access to a lapidary, or lapidary equipment, this
process can be done manually with sanding sticks… be sure to use
plenty of water to wash away debris and keep the stone cool. In this
case I would probably hold the sanding stick down, and rub the face
of the stone against it, frequently dipping in a cup of water. With
patience, this will be equally effective as a machine method… it
will just take longer.

Hope this helps!

Dave

Dave Sebaste
Sebaste Studio and
Carolina Artisans’ Gallery
Charlotte, NC (USA)
dave@sebaste.com


#4
   I have a ring set with a flat top boulder opal. Over the years
the opal has become scratched. Is there a way that I can re-finish
the surface of the opal, easily and gently w/wo removing it from
the bezel setting. Thanks, in advance, for all help. 

there are times when it makes more sense to have someone who knows
what they are doing do that sort of thing. i cut stones, i do metal
work. i have spent alot of time to become skilled. there is a
learning curve. never attempt to do work you have no skill at unless
you are willing to accept responsibilty for the worst possible
results, if you can live with that, use gemcutting equipment like a
genie, sand and polish carefully. there are flex shaft tools that
work, but it is tricky. contenti distributes course and x-fine
silicon wheels to fix stones. i have not been able to use the course
and go to the x-fine with good results, i have been able to use the
x-fine to take out fine scratches on faceted stones. their catalogue
#'s are 442-817 and 442-747.