Occasionally I have a stone that is very lightly scratched, not
visible to the naked eye, but I can see it under 10X magnification.
I’m not a stone cutter so I don’t have lapidary tools at my disposal.
Can I polish the scratch out with my Foredom ? If so with what
attachment or compound ?
Brian Corll
Brian Corll, Inc.
1002 East Simpson Street
Mechanicsburg, PA 17055
Can I polish the scratch out with my Foredom ? If so with what attachment or compound ?
In a word, No! But there are those who probably disagree.
K Kelly
Can I polish the scratch out with my Foredom ? If so with what attachment or compound ?
Really depends on the stone. I’ve had some success with up to
corundum if the damage is small. There are small diamond discs that
work well. The trick is to keep the tool flat with the surface if its
faceted, even a slight deviation and you may find yourself adding a
facet. As you might imagine too much cutting and you will affect the
pointing up of the facet junctions, which can be worse than the
scratch. A steady, consistent hand is needed.
For cabs, you can get a leather wheel for the buffer, around $40 I
think, and charge it with required diamond grit. A regular bench
grinder fitted with an expanding drum for abrasive belts works very
well…quick change, wide choice of grit, not a budget breaker but
not cheap. A brush charged with diamond grit on the flexshaft will
sometimes work too.
You must start with an appropriate grit number and progress from
there. If you try to use just a very fine grit you will just round
off the scratch edges, making it more visible, and blurring the area
in general.
But really, if you need 10X, it’s eye clean. Is the pursuit of
perfection worth the trouble?..Given that even unlikely problems
have a way of appearing at the worst time, like when your customer
is due any minute for pickup!
If the stone is faceted, there isn’t any way I know of to polish a
scratch from a facet with a flex shaft without rounding the facet
junctions. Cabochons, however, are another story. This is the same
setup I use for polishing carvings.
First, there are two types of cup brushes available for your flex
shaft. Basically, they are permanently mounted on a mandrel with
bristles that face down and slightly out from the tip of the mandrel
in a sort of cup shape. White bristles are stiffer than black
bristles. I have a few of both types for each of several grits of
diamond paste I get from Graves Company. These diamond pastes come in
syringes that you use to squeeze a drop or two out at a time. There
are also diamond sprays, but I’ve never used them.
Load the cup brush with your chosen grit They’re available from 240
(I think) to 100,000. For very light scratches, I’d probably start at
600 and work my way through the finest, working the brush evenly
around the entire stone using moderate speed with the flex shaft.
This is so I can get the same final polish on the whole stone.
Keep the brushes with the same syringe of paste (it’s a greasy
paste) and always use the same brushes with the same grits, and clean
the stone thoroughly with degreaser between each grit to avoid
contamination.
Some stones will final polish nicely with 50,000 grit, others will
require 100,000. Still others will polish best with a powdered oxide
such as cerium, tin, aluminum, Linde A, etc. Some of those oxides
will work better on leather, some will work better on felt and none
will work with the cup brushes. It mostly depends on the stone. Many
soft stones will polish best with Fabulustre or Holy Cow on a muslin
buff, which also puts a good polish on sterling. Sometimes lapidary
can be as complicated as gemology.
If you have a facet larger than the cup brush, you may successfully
polish out the scratch without rounding the facet junctions (i.e., a
table facet), but chances are the facet will be visibly concave. A
link to Graves’ diamond paste compunds:
http://www.gravescompany.com/polishin.htm Your supplier of flex shaft
attachments will have the cup brushes.
I’m not affiliated with Graves, but the coralnut is - perhaps he can
tell you more.
James S. Duncan, G.G.
James in SoFL
Brian,
If the stone is a faceted one, the answer is a resounding “NO!”. The
facets are flat, and I mean REALLY flat. Putting a wheel to them
will ruin the surface and probably increase the damage. A simple
re-polish of a facet, even a table, is very inexpensive. And I’ve
yet to see a native cut stone under 10X that didn’t have some
"cat-whiskers" here and there or much worse. In fact, most of them
are painful to look at. The human eye can detect “non-flatness” on a
plane and polished surface that is less then 1/2 a wavelength of
light out of whack. You can’t come close to that with a Foredom.
Polishing of a gemstone is an art unto itself, at the highest levels
of quality, and CAN be demanding of technique and machine…but
usually it’s pretty straightforward with the newer laps recently
developed and the proper use of charging abrasives (diamond).
The problem I encountered on the learning curve many years ago is
that a professional cutter or hobbyist, using modern techniques, is
almost forced to re-do the whole crown, I.e., every facet, because
when just one is done it looks so much better than the others that
it stands out. Typically, overseas cutters use 8000-14000 grit
diamond on a tin lap to polish sapphire. Here we routinely use
50,000 to 100,000 grit, and sometimes 200,000 on a ceramic lap. The
ceramic lap is much harder than tin and gives a crispness to the
facet edges (and accompanying brilliance) that has to be seen to be
appreciated. Sometimes, I will kiss the facets with a slight touch
of alumina to further give the facet a “wet” look. This sounds
great, and it is, for a sapphire (natural or synthetic) that I cut
from scratch, but if I re-polish a single facet on the crown of a
commercially cut sapphire, oh boy! Does NOT match the rest of the
stone! So, I routinely use 14,000 grit on the repair or re-polish of
commercially cut material, just so it matches the rest of the stone.
Kinda sad, huh?
Wayne
Brian,
Try contenti.com
Go to “Swifty rubberized abraisives scratch removal series”. These
mount on a flex shaft mandrel. There is a course and a fine. The
course is, and in my experience if you use the course, the fine is
too fine to polish what the course does to some stones. It will
leave a granular surface. If it is fine scratch, the fine will
polish it out, you have to keep working it with a good circular
motion slower speed.
On some faceted stones, if my customer bought a “gem” that has a
facet with a lot of lines running parallel, not cut and polished
well, I can go over the facet and clean it up somewhat and get it
looking better. Sometimes it just polishes the grooves, but it still
looks better. I have had success with garnet, quartz, and corundum.
Richard Hart
If the stone is a faceted one, the answer is a resounding "NO!". The facets are flat, and I mean REALLY flat. Putting a wheel to them will ruin the surface and probably increase the damage
First of all, it takes knowledge and skill to use a flex shaft to
fix a facet, but In the context of having a retail jewelry store and
doing repairs, and also having done faceting and having a good dose
of the obsessive compulsive nature that is required along with
extensive patience and knowledge and persistence required to do
faceting and be happy with the end result, that I can show my work
to another facetor and not have insecurity about what they are
thinking…
I have found that any improvement on a scratched or abraided stone
will make my customer happy. They are looking at their ring from 1
to 1 1/2 feet away, and usually a little better is all they want.
You cannot recut a 6mm garnet or amethyst, you would be better just
replacing the stone. If it is that sentimental ring passed down from
Aunt Matilda, they just need it to look a little better while they
continue to knock the crap out of it with daily wear.
Despite best intentions, sometimes a sapphire can get nicked with a
graver while setting, right where the bezel meets the stone. I have
polished a really small light scratch this way. Some gems have
rounded facet junctions any way, so it is no big deal.
I always tell my customer it will not fix the problem, it will make
it look better than it did.
There is an old trick that gets passed down, with malachite or
lapis, if there is a small scratch rub it on your nose, the oil will
make the scratch disappear.
No matter how much time and perfection is spent faceting a gem,
please remember, if it is a ring, the customer is going to beat the
crap out of it over time. I just try to help them get more use out of
it with cosmetic repair before they need to replace it.
Sort term fix for a long term problem, but it seems to be what they
want when offered the options.
James,
Thanks for the info. I was about to set a citrine the other day when
I peered through the 10X and saw a tiny scratch on the table. It’s
not visible to the naked eye, but it’s there and it bothers me ! The
cups I have are smaller than the table so I think I might try the
diamond paste and see what happens.
Thanks for the info. I was about to set a citrine the other day when I peered through the 10X and saw a tiny scratch on the table. It's not visible to the naked eye, but it's there and it bothers me ! The cups I have are smaller than the table so I think I might try the diamond paste and see what happens.
You’re welcome, Brian. In the other post, I said I’d start with 600
grit, but that was for a cabochon. In this case, I’d start a bit
closer to the polishing end of the grit spectrum, just to make sure
you don’t remove too much material. Say, 1200 or even finer.
James S. Duncan, G.G.
James in SoFL
Richard,
Yep, I have Swifty’s in my “polishing stuff” drawer. Since I started
using them I don’t bother with rouge, felt or anything else to polish
my jewelry. They do a fine job. I wondered about using them but I
wasn’t sure I wanted to try. Thanks for pointing that out.
Brian
If the stone is a faceted one, the answer is a resounding "NO!". The facets are flat, and I mean REALLY flat. Putting a wheel to them will ruin the surface and probably increase the damage
I sold my lapidary and put in a machine shop, but I kept my diamond
polishing kit. If one gets a little scratch from a rubber wheel or
graver in anything up to sapphire, it’s easy to polish it out, it
just takes great care. I use masonite or thin plywood, drilled on a
center and then turned into a wheel, like a lap. No, it will not be
as crisp as a real polish, but if you’re careful it can be good.
Especially when it needs to be NOW!!
Hi Richard,
Understood and accepted. But I could never do it, because my
competition down the street will loupe it and disparage the work.
Customers, even the loyal ones, will not hesitate to ask another
jeweler’s opinion of your or my work. Been there of then enough, and
I like to win the contest.
I understand completely how it is to commiserate with the customer
and have an understanding that it is a “good enough” repair…but,
sorry, it’s not good enough to have MY name on it!! Not arguing,
flaming or chastising, just saying…
Wayne Emery
The Gemcutter
Hi Brian,
…And, in this corner… I’m with Wayne and Kevin: leave
goldsmithing to goldsmiths, and lapidary work to lapidaries. I know
how trite that sounds, but you’d be amazed at how much of my annual
income is derived from goldsmiths and silversmiths who’re of the
opinion that gemcutting is just a matter of going "zip, zap, zoop"
with their Mizzy heatless wheels and silicone polishers, after
deluding themselves into thinking that all abrasives are universal
in their applications. The fact is that, just as it’d probably be
unwise to try to remove firescale with an onglette graver, to chase
smooth surface porosity with a millgrain wheel, or try retipping a
prong with an arc-welder, the tools at a metalsmith’s bench are
designed and constructed with the working characteristics of metals
in mind, and those on a lapidary’s bench are equally specific to the
surface dynamics of stones. Suffice it to say that I have both a
lapidary shop and a metalsmithing one within my studio, and the only
tools which ever move back and forth are those used for either
magnification or measurement.
If you can wait the two to three weeks until I have some time in my
schedule, I’ll be more than happy to remove those scratches for you
– write to me off-line for a copy of my rate card, if you wish – or
you can locate someone in your general area. But, either way, you’re
probably vastly better off leaving the task to someone who’s equipped
with the right tools to handle the job, than trying to make some of
yours fit the bill. Doing otherwise is more likely than not to
increase the size of your lapidary bill, instead of saving you from
paying one.
Best of luck,
Douglas Turet, G.J.,
Turet Design, LLC
P.O. Box 242
Avon, MA 02322-0242
Tel: (508) 586-5690
Fax: (508) 586-5677
Use a very very small amount of diamond paste or you could make the
scratches deeper. Also, make sure it’s a scratch and not a pit or
you stand the chance of ‘grooving’ your table for something you can’t
polish out. Better yet, if you have some cerium or alumina use that.
Craig
www.creativecutgems.com
Wayne,
I understand both sides, just relating from the retail reality, where
sometimes customers do not want to spend as much on a repair as they
spend on a latte. And it is usually in the context of doing some
other repair on a piece, they ask if I can polish the stone, I quote
a price, and they decide to just do the re-tip, and I will
"re-polish" with a silicone wheel for free. Just dresses it up a
tiny bit, and I get appreciation for any improvement. Keeps those
repairs coming in. (Damn!)
Richard Hart