Diamonds and Sapphires

I was told by a teacher that diamonds and sapphires are so
strong you can file over them and not nick them. This was
during a stone setting class. Today I am going to set some
diamonds and sapphires flush in a ring using the hammering
method I was taught and I am going to need to do a lot of clean
up. Can I file over these stones?


Hi Dede, Don’t file over the stones. Technically, they are
harder than the file. They are also comparatively brittle. Any
stone can become abraded if you run a file over it. You will also wreck the file.
Sorry, Tom Arnold

Dede, I wouldn’t recommend ever hitting any stone with a file.
If you are using a file to clean up your prongs, first remove ALL
the edge from the file with sandpaper as it can easily chip the
girdle. I think most of us use the sanding discs to clean up
around stones these days. It really doesn’t take a whole lot to
nick a stone, and you’ll end up doing plenty of that if you hit
them with a file. Mike.

DeDe, I would not. Diamonds and sapphires are very hard, but you
could not begin to guess the number of stones I have repaired or
replaced that had chips from careless filing, grinding, and
buffing. It is not the hardness that comes into play. It is
the sharpness of the facet junctions that are so vunerable.
They abrade, chip, and even break from materials which are much
softer than themselves. Finish the prongs as close as possible,
set the stone, then lightly buff. Silicone carbide. hardened
steel, and diamond tools will easily ruin a good stone.



I’m going to assume you misunderstood your instructor, or he/she
did’nt understand your question. The idea of an indestructable
gemstone is a myth. I don’t care what kind of stone you’re
dealing with. If you file across it with a steel file, you’re
gonna damage it. Perhaps not in any obvious way but when louped,
you’ll see it. Chipping and abraiding are the most likely
result. You can feel fairly safe about emerying over a diamond
but not a saphire.

Be careful out there;
Steve Klepinger

Hi, Diamonds and Sapphires are tough but they do crack/chip if
you hit them in just the right(wrong) spot so you really should
avoid filing and hammering directly on the stones. Invest in some
blue rubber(abrasive) wheels and clean up with those. You can
shape the blue wheels into a nice sharp edge and smooth the
surface right along your bezels and prongs without hurting your
Diamonds and Sapphires. They will damage softer stones though so
be extra careful with those. They have all sorts of small
polishing wheels for the flex shaft. Check out any jewelry supply
catalog for more info on them.Newport, RI -July 31, 1999 the place to
be. Email me for Metalsmith gathering info.

Kathy, A file racing along a sapphire will not scratch it.
However, each tooth on the file will act as a hammer. The file
will not touch the middle of a facet. It will normally hit only
facet junctions. Imagine a couple of hundred hammer strokes on a
facet junction in a second. Then imagine a few seconds or a
couple of minutes. Even a sapphire will give at some point. I’ve
learned this the expensive way. Trust me. Diamonds are a little
better about this. They will just bust all of the teeth off of
your file. It is usually a better idea to use pumice wheels and
gravers to clean up around settings and to use a file carefully.


Bruce D. Holmgrain
Maryland’s first JA certified Master Bench Jeweler

Dede Hello!

Your post indicates your fairly new at stone setting. Believe me
we all were once. I learn plenty from this forum and am happy to
contribute occasionally.

Don’t ever touch a file to a gem even gently. The main reason is
you can chip or abraid even diamonds. It goes without mentioning
the damage some stones could do to a perfectly good file.

Instead concentrate your efforts in the process of stonecutting,
with cutting a perfect seat. All that you need to do be it
bright cut, channel, gypsy, etc., is get the stone in deep
enough with a correct (not oversized) seat, and you will have
room to do your cleanup without damaging stones. Even with the
most concave, difficult areas to set stones; if you proceed
slowly, and confidently you can have enough metal to work with,
and minimize cleanup. Take your time, cut your seats as
precisely as you can, and use non stone cutting rubber wheels
near your stones. Any rubber wheels are OK with diamond.


DeDe, You had better be more safe than sorry. When filing your
metal around stones always file away from the stone. Let’s say
you have a flush set round stone on the top of a domed ring. By
gripping your ring mandrel and leaving your thumb in an upward
position rest your file on the side of your thumb and file away
from the stone. You thumb may give you a brace or guide. You may
even place your thumb on top of the stone to make sure you file
away from the stone. I have seen facet corners nicked with files.
You never can tell when a vulnerable area is on any stone. By
practicing this technique you can set even very brittle stones
and clean up around the prongs or edges and no damage the stones.
You may even take a small needle file and polish the edge that
rides on your thumb. This will again keep a sharp edge away from
damaging any stone and you won’t cut your thumb on a sharp file

TR the Teacher & student

If you need to use a file close to a stone, try a barrette file
which has no serrations on the edges, and hence should not
damage the stone. >D<

If you need to use a file close to a stone, try a barrette file
which has no serrations on the edges, and hence should not
damage the stone.

In fact, I was taught to use a barette file to finish prongs. We
were also advised to emery off the edges of the files because
they will damage anything softer than a diamond. Personally I am
convinced that even a diamond can sustain damage if swiped at
just right. Particularly the girdle. A pumice wheel is a much
safer bet.


Bruce D. Holmgrain
Maryland’s first JA certified Master Bench Jeweler

Hello Bruce! Well said! If I could humbly expand on the barrette
file. If a barrette file is prepared and used properly, it is
indispensable. The only cut I use is the #6, for prong work. It
is ultra fine, which eliminates catching a girdle nick. I use my
emery board with Norton #2 emery to take the cut lines off the
side of the file, and then #0. The 73/4 inch I prefer because
you have a longer throw with it, and better balance. Use a
lifting stroke, together with a twist in your wrist, to finish
prongs. There is a #8 barrette available as an escapement file.
The cut area is only 2" long. Useful only when nothing else will
do. It cuts, but it looks like it’s polishing. If you do not
"lift" you will abrade the facets of your set stone. Other than
diamond. Tim