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Nicked gem polishing


#1

Hello all, While setting a rhodalite cab yesterday I nicked the stone
with a punch. I know I can polish it if I had the correct flex
shafts wheels. I have tried charging felt buffs with diamond paste,
and found that method wasn’t aggressive enough. I think I need a
pre-charged product, if it exist. Perhaps something used by gem
carvers that will allow me to get into a tight spot.

Thanks for any help and direction.
Peace,
David
dagronick@ail.com
(Maine)


#2

Hi David, I know that the contenti Co. ( 800-343-3364 ) Carries
rubber wheels specifically made to remove scratches and nicks in
stones . I’m sure other companies do also… Ask for Arthur or
steve and I’m sure they can help. Daniel Grandi

We do casting , finishing and a whole lot more for designers,
jewelers, stores and catalogs. Please contact
sales@racecarjewelry.com or call 401-461-7803 to have your
products made for you.


#3

David, Garnets are particularly sensitive to the heat generated by
abrasion. They crack and chip very readily. I suggest you make
several small wooden wheels by drilling a hole in a dowel rod and
cutting off the drilled end. Place the wheel on an end drilled
mandrel and true it up by running it in your flexshaft against a
piece of sandpaper. Next charge your wheel with 600 diamond and
lubricate the process with mineral oil. After the chip is ground out
with 600 you will have to progress to the following diamond grits.
1,200, 3,000, & 14,000. If you want a finer polish go to 50,000.
This should be a quick and easy project.

Gerry Galarneau
@Gerry
www.galarneausgems.com


#4

David, alumina (linde A) makes a much better polish for garnets.
You can get mylar charged disk in both 6" and 8" sizes from most of
the faceting machine suppliers. You could eaisly cut the disk down
to flex shaft sizes. One manufacture is Crystalite. These depend
on a smooth surface though, and will be very slow if effective at
all for surfaces with scratches larger than those imparted by
600grit paper. If you have a nick, sand it out first, then attack
the sanded area with the polish. The finer the “pre-polish”, the
quicker the polish will develop. While this sounds like a lot of
additional work, it is actually faster than trying to polish out a
deep scratch or a nick, and a lot less likely to damage the stone
due to overheating.

Don


#5
   Hello all, While setting a rhodalite cab yesterday I nicked the
stone with a punch. I know I can polish it if I had the correct
flex shafts wheels. I have tried charging felt buffs with diamond
paste, and found that method wasn't aggressive enough. I think I
need a pre-charged product, if it exist. Perhaps something used by
gem carvers that will allow me to get into a tight spot. 

elt just soaks up the diamond compound, leaving nothing at the buff
surface to do anything. Instead, try making small wheels from wood
dowel cutoffs. Slice a bit of dowel off, drill the center out, the
spin against files, etc, to true up the shape, and then sand smooth.
Now use just small amounts of diamond compound on the mini wood laps.
If the nick is substantial, you’ll probably have to use several of
these, starting with a coarser grit, say peryaps 1200, and then move
up to finer grits. If you want to spend money on stuff, you can
also get small (half inch, to inch, or thereabouts) mandrel mounted
rubber disks, to which you glue (lapidary contact cement) matching
little disks of the treated canvas cloth used in traditional diamond
polishing pads. They work well. These can also be used with oxide
polishes. And for quick fixes of minor nicks, some of the rubber
wheels put out by pacific abrasives, and others, use aluminum oxide
abrasives, which will also affect these stones. The ones I’m
thinking of are white in color, quite hard for a rubber wheel, and
will leave a moderate degree of polish on the stone as it abrades
into the stone. The only trouble with these methods is that it takes
considerable care to get a polish on a nicely shaped surface, instead
of a nice polish on a visible gouge that your attempts to repair the
stone have now produced;. Especially rignt next to a bezel or a
setting, it’s difficult to maintain a surface that still looks as
though you didn’t damage it and then repair it. And one final
comment, for very minor scratches on softer stones, the platinum
polishing compounds sold by Gesswein, which are micro graded aluminum
oxide, will affect many stones too. The 8000 rouge compound does a
quite passable job of restoring the gloss to softer stones, just as
it does to the metal. You have to be careful to avoid overdoing it,
or you get orange peel effects. These compounds, which I LOVE,
are not without danger, as a result of this. Polishing a piece set
with a cab is cool, as the most it will usually do is improve matters.
But facetted stones look better when they don’t have all their facet
edges slightly rounded over and highly polished… Nuff said…

Peter