Setting stones with thick girdles

hey all

I have often heard that the ultimate goal of a stone setter is to set
the stone with no gaps between the stone and the prongs so how do
some of you more experienced setters set stones with really thick
girdles or uneven girdles.

guy g.

Any stone setting is essentially inlay work. Even a diamond is not
just set into prongs with a notch whacked into it, the bearing is
cut, checked, adjusted, until it is a good fit, and then the stone
is set. The more important the stone, the more this matters. You can
pull the hart bur up and down the make the gap wider, and also push
it downwards at an extreme angle to make the pavilion angle steeper.
On a really fat girdle I like to use a cone square bur and actually
make it more of a rounded notch instead of the triangular shape that
a hart bur leaves.

Guy, and all on Orchid ! It’s me again.

These notes on setting techniques are now going to be presented at
my four seminar classes on the Friday. this will be one of my
hand-outs of Claw settings also. I will be at the "Bench, Conference"
on April 27-30th in Denver, CO. Come on down and join “us”. I will
also be giving two days of live setting demonstrations on Saturday
and Sunday. Drop by, and say “Hello”.

Now to continue on with these setting notes. I don’t have much
experience, maybe 12,267+ working days (47 years) might be in
order…:>) You are right, the ultimate game plan is to have the metal
bond with the stone. No gaps, or spaces, or even a maligned claw to
the stone. So how do I do it? Don’t’ tell anyone, it’s a “trade

In some of my postings, I do mention a strange little item of joy
its called a Bud Bur, I call it my “Buddy-Bur”!! It has a SQU number
of “6” don’t ask me why, but that’s the generic description of it. In
fact, in my second setting book, I fully explain the merriad of uses
for this remarkable little tool, a.k.a. “Bud Bur”. One of these
little secrets, per se, is to help the setter to exactly mold the
claw right to, and over the claw. This is right at the pivot point of
the girdle. Many times THIS IS JUST WHERE the spaces can occur. This
space also occurs at the area where the Pavillion of the stone meets
the metal claw. So how in heck can we create a near-perfect seat for
this stone? Her are my answers to those who need to know.

(1) For the thick girdle, I use a bud bur at a size, not to exceed
bur width of #006,the measurement really means it is.006 mm’s in
width. If you select a bur width of #008 or a greater number you,
will have another space to contend with, bad news! Generally a bur
width #005 is too fine to use in this setting process.

I will ask you, and all, who are reading this to get your fresh or
new bud bur, and at the exact point of where the girdle is to sit use
this bur and grind a little metal away. You are now making larger,
the sharp “V” shaped cut made by your 156C or undercutting bur. You
are basically widening this V-cut!! Plain and simple, right? “Thou
Shalt not proceed to cut FURTHER INTO THE CLAW”.

(2) If you are trying to set a stone with uneven girdle, I again,
will use the bud bur and carefully scribe at the inside of the slaw
just where that apart of the stone will meet the metal. Once you have
decided use the bud AGAIN, and proceed to cut a shade deeper INTO the
claw. Now you can use your 156C and go the regular process of setting
the stone, Do not change where the stone is to sit. You have to make
the corporate decision and not to rotate the stone once the stone has
been fitted. You are making this a “specially contoured” adjustment
just for this poorly cut stone. Got it?

(3) Finally, for the areas with a Pavilion that are to meet the
claw. Another use for the “Buddy-Bur” file. I use this fantastic bur
as a “Mini-File” I could use a larger bur of maybe #007-#008 and to
proceed this filing maneuver right from the junction point of the "V"
and follow the metal right down to its base, or where the Pavilion
falls away from the claw. I use this bur held horizontally and
scrape, or remove the metal that is not allowing the stone sit
against the metal claw. Be ruddy careful and not scallop away too much
metal in this process, lest you make a very uneven ‘file’ cut. You
might be defeating this whole process. You should practice these
steps till you go the hang of it. It might take a few years to
’master’ these techniques.:>)

Remember this, I prefer to use a 90 degree angle bur, not the
shallow 70 degree angle. The 90 degree is almost the same angle as
the stone you are trying to set.“156C”, “under-cutting bur”, “bearing
cutter” and lastly the “under-cutting bur” are all the same bur. Some
tool suppliers use different names for the same thing. What I have
been telling you all is a trade secret so don’t’ tell anyone please,
or I might be inundated with threats of giving away secrets… !

Always here to help those who need help. Gerry Lewy! a.k.a. Gerry,
the Cyber-Setter!"

Hi Guy;

so how do some of you more experienced setters set stones with
really thick girdles or uneven girdles. 

For prong setting, I assume. With smaller stones, I simply cut the
notch with a 90 degree bur and once I’m in to the depth I want, I
bear down on the lower angle of the notch, where the pavilion would
seat, cutting deeper towards the bottom of the prong. For larger
stones, I make a saw cut with a 3/0 blade, then go into that cut
towards the back of the prong with a cylinder bur that approximates
the width of the girdle. Then, I get another 90 degree bur and cut
the upper and lower parts of the notch, leaving the gap created by
the cylinder bur, and creating an angle that is slightly more open
than the angle created by the pavillion and crown of the stone. This
gives me a notch that matches the edge of the stone when the prong
closes down on the stone. Finally, to close in the prong, I use
setting pliers, the kind with the slightly parallel jaws, one jaw
slightly shorter than the other. I modify mine so that the shorter
plier jaw has a notch cut across the very end of it, sort of like a
finger nail. The longer jaw is braced against outside of the
opposite prong, and the tooth of the plier jaw bites into the top of
the prong that is being bent in. When the jaws are tightened, the
prong is being pulled in towards the stone at the same time as it is
being bent over the crown. Finishing is done with a barrette
escapement file, fine cut, with a polished safe edge. The filing is
done from the inside contact point of the prong, out and over the
top, rounding and forming, so contact with the stone is minimal, only
barely touching just before the stroke. Finally, a light blue rubber
wheel to smooth things up. For stones that are vulnerable to even
polishing, I may shape and polish the prong previous to setting the
stone, then I only need to clean up the slight plier marks on the
outermost parts of the prongs, and this I can do with a pink rubber
wheel, which won’t mar the stone.

As for bezel setting these stones, I generally set heavy bezels, so I
use a round bur with a bur stop, the kind that you attach to the bur
with an Allen wrench. These are a sort of poor man’s All Set. The
ball bur should be big enough to cut a hinge in the inside of the
bezel at the level where the stones girdle will be, reducing the
thickness of the bezel to around 0.5 millimeters or less. The bur’s
diameter should create a rounded notch all the way around the inside
of the bezel coming almost to the top of the bezel’s inner edge.
That way, when it’s hammered down on the stone, only the uppermost
edge of the bezel touches the stone, making contact above the girdle
so as to not put any pressure near the edge of the stone. Sometimes,
before I hammer in the bezel, I file the top of the bezel at an angle
sloping downward towards the outside of the bezel. That way, when the
bezel comes in and starts to toughen, I can continue to bring it down
on the stone by shifting the angle of the chasing tool upwards,
hammering more or less straight down on the top edge of the bezel.
Last thing is a flat graver, very sharp and polished, but with the
leading corners dulled very slightly so as not to scratch the stone
if they make contact. Sometimes, I burnish the inside with an
annealed stainless steel burnisher. If the stone is really soft, I
use a pink rubber cylinder to polish the inside edge.

David L. Huffman

This may be a stupid question but why do the stones have uneven or
thick girdles? Are they just poorly cut?


Hi craig

yea mostly they are poorly cut. we do a lot of remount work and alot
of the stones are old irregular cuts or from low end jewelry to
begin with. dave and gerry thanks for taking the time to explain
your tech. in detail.

thanks much
guy g.

Thick girdles are especially prevalent in color stones, as these are
cut deep to improve color. Make sure to practice using your loupe 10x
and your optivisor as to see the seat being cut for the stone. Try
practicing with heart shape cz’s as these will give you practice on
cutting seats for a deep cut stone.


Thick girdles are especially prevalent in color stones, as these
are cut deep to improve color. 

The girdle is the widest part of a faceted stone. the top is the
crown, the bottom is the pavillion. If the girdle is thick, it will
made no difference in the color of a stone, unless the color is
concentrated only in the girdle.

The pavillion of stones can be cut deep to improve color. I heard
while at G.I.A. that a yellow diamond’s color can be improved
(temporarily) by coloring the girdle with a blue marker. This
practice of leaving more material in the pavillion makes the stone
weight more, and cost more, but not necessarily adding any value,
usually not better color.

Some types of cutting add more brilliance to the stone, and this
makes the stone look lighter, so “native cuts” can be less brilliant
and the color looks better, but not because there is more material,
because it is not refracting as much light , and it appears to have
deeper color.

Richard Hart