I set a Chrysoprase cabochon in a 14K yellow 6-prong setting. After
setting the stone, I polished the 14K yellow setting with Tripoli and
Red Rouge with my flexshaft, trying to be very careful of the stone.
When I compared the set stone to the unset Chrysoprase stone, I notice
that the set stone’s shine was a bit dull. From previous posts, I now
know to tape off the stone!!
Question: What do I use to polish the Chrysoprase. I have other
Chrysoprase stones that also need polishing.
I will take a stone setting class, but until I do, Orchid is my
classroom. I will also get “Classroom in a Box” by Blaine Lewis. I
have most of the Revere tapes and have done my own version of the
projects.
Thank you Hanuman and all Orchidians. Members of this forum are so
generous with their hard learned You are all treasures in
this world.
Question: What do I use to polish the Chrysoprase. I
have other Chrysoprase stones that also need polishing.
I will take a stone setting class, but until I do, Orchid is my
classroom. I will also get "Classroom in a Box" by Blaine Lewis. I
have most of the Revere tapes and have done my own version of the
projects.
Thank you Hanuman and all Orchidians. Members of this forum
are so generous with their hard learned You are all
treasures in this world.
You should buy John Sinkankas’ book “Gem Cutting”. It’s basic if
you’re interested in stone cutting. Your chrysoprase answer is there.
Question: What do I use to polish the Chrysoprase. I have other
Chrysoprase stones that also need polishing
It is all but impossible to really polish out at stone in the
setting. You end up with a shadow around the bezel or prongs.
For unmounted stones, mount the stone on a dop stick (a wood dowel)
using dop wax. Check the surface to see if there are any scratches
for marks from the initial cutting of the stone. You can work out
the scratches using just wet or dry emery paper If the surface looks
good, just sand it with 600 grit, If there are scratches deeper than
that, start with 320 and work your way through 600. To do this, lay
the paper in the palm of your hand and add some water. Using the dop
as a handle, slide and rock the stone back and forth until you have
removed all of the scratches that are coarser than the paper you are
using. Clean off the stone and dop between grits. Once you have a
clean well sanded surface, you are ready to polish the stone. You
can use a piece of leather that is damp, sprinkle on some Cerium
Oxide or Linde A (alumina) polish. You can polish it out by hand but
expect it to take a while. To get the best polish, you will need to
apply considerable pressure to the stone. You can make a polish
disk for your flex-shaft by taking a large diameter, pre mounted
wire brush (1" or larger). Cut a disk out of a piece of scrap
leather and use rubber cement and glue the disk (shinny side down)
onto the brush. You want to make sure that the leather extends
beyond the bristles so they can’t get to the stone. After the glue
has set, you can then dampen the leather and apply the polish and
work out the stone. Use a slow speed. Faster isn’t better when it
comes to polish. Keep the leather damp. It should drag on the stone.
If it drys out, it will generate enough heat to break the stone. One
more point, just like “faster isn’t better” more polish isn’t better.
The classic polishing method for all quartz minerals is a cerium
oxide slurry (with water) on felt. Pellon, such as is used for shirt
collar liners, is also good. If you use pellon, be sure to use a
rubber backing, since the more that the cabochon conforms to the
backing, the easier the polish will be. If the felt isn’t thick,
mount it on rubber, too. Leather could also be used, if that is what
you have around, but isn’t considered as good. If you don’t have
cerium, you could try Linde A (alumina), which should also work. My
books state that even tripoli will polish it, but I am not sure about
that, given your experience.
Question: What do I use to polish the Chrysoprase. I have other
Chrysoprase stones that also need polishing.
Hello Yvonne, I have always used tin oxide on a felt wheel to polish
chrysoprase. You may try to use a 1 inch felt wheel on a flex shaft.
This may get messy! Dampen the wheel and apply polish. Apply to
the stone at high speed. Be very careful of heat build up, or you
can easily develop white spots where the stones crystals pop.
Chrysoprase has lots of quartz (silicate) and will polish with cerium
oxide as well. You can get small quantities from someone that
tumbles rocks or does glass and windshield repair(for autos). It is
best to remove the stone and polish evenly, but this will help. If
it is a scratch, you will need to remove it and go through sanding
before polishing.
Question: What do I use to polish the Chrysoprase. I have
other Chrysoprase stones that also need polishing.
Tin Oxide with a leather buff works well. Basil (sheep skin leather)
works well stretched over a backing plate on a motor shaft, cow hide
also works but these leathers should not be oil cured as they become
slippery when wet.
Make a thick slurry of the tin oxide using water and brush a little
on to the dampened leather buff.
Work the stone around on the revolving buff and as the moisture dries
you will feel the stone start to grip on the pad, at this point you
should be getting a good polish.
Add more tin oxide if necessary.
You could punch small circles out of stiff leather and use them with
the same result on small spindles on your flex shaft.
I use this latter system to polish jade carvings using various grades
of diamond paste… If you have diamond paste in grades around
3000/8000 it should also work on Chrysoprase.
To polish your loose stones on a revolving buff you will need to
attach dop sticks to the back of the cabs to give you some control.
Suggest you talk to your local rock shop if there is one handy re
means of sticking the dop sticks to the cabs. People seem to have
their own preferences for this… I use araldite epoxy resin but some
people seem to find this too hard to remove.
You should be able to polish to a high shine with a hard felt buff
with alittle diamond powder14,000 mesh if your marred surface isn’t
too deep. I have more action if I use the dry diamond powder with
alittle water to apply to buff. Crystalite is the company but I’m sure
there others. Its always good to have on hand for such occasions.
It is the variable nickle content and unusual structure of
chrysoprase which make polishing difficult. I get my best results
using chrome oxide on leather. I recommend to all of the jewelers and
goldsmiths I cut for that they avoid using tripoli around any set
cabochon stones, because the active agent in tripoli is quartz and it
will take the finish off most normal cabs.
Will cerium oxide work for display cases? Mine has a few scratches on
the top that I would like to remove. Is it possible to do this job
myself, or should I call a service? Thanks for the help! Susan Ronan
Your question and recognition of the wonderful people on Orchid
deserves a polite response. The Sinkankas book Gem Cutting refers to
Chrysoprase as follows; Cryptocrystalline Variety, “Bright
Yellow-green chalcedony stained by a nickel mineral. Troublesome to
polish; its peculiar structure leads to undercutting unless polished
on leather. Heat gently for dopping or the delicate color will be
driven off.”
A friend Dick Friesen is a polishing expert , he can be reached at friesenr@ix.netcom.com an e-mail to him may give you better
I hope this helps, I am copying Dick in so he will know you may
contact him.