Percent breakage for stone setting?

I am trying to get a handle on the average breakage of precious and
semi precious stones during the numerous setting procedures. Ie.
Prongs, burnish, pave’, channel, etc.

I know there is variations in stone type, ie. Diamonds vs peridot

And stone size 1.5 vs 4mm

And in stone shape, round vs princess cuts.

So I would love to hear people experience when setting. When do you
order extra stones for breakage? How many do you order when you do?

When I am done compiling this I will post the results.’


So I would love to hear people experience when setting. When do
you order extra stones for breakage? How many do you order when you

If I can afford it, I always order 2 or three extra stone than I
need. (More to feed the trolls under the desk than for breakage)

I am trying to get a handle on the average breakage of precious
and semi precious stones during the numerous setting procedures.
Ie. Prongs, burnish, pave', channel, etc. 

Rule #1 for setting is NOT to bust stones. Mistakes do happen,
usually caused by the naked hairless ape with the tools.

Cheap and fragile stones in tough settings and I might buy a couple
of extras (at customer expense) and expect to add them to my

Busting a 25pt diamond takes more skill and deeper pockets than I
have, although stones with pointy corners are easier.

Setting is not rocket science, although being slightly anal really
does help. Hell they even let sort of old folks who can’t see none
too well do it.

Demand Designs
Analog/Digital Modelling & Goldsmithing

Many years ago, when I was still pretty new to stone setting, I was
going through a period in which I was breaking a lot of stones. I
called a friend that was far more advanced than I was and asked him
“How do you keep from breaking stones?”

His answer, as over simplistic and seemingly arrogant as it was,
turned out to be the absolute truth - “I just don’t break them.” He
expanded on the thought, telling me that if I was breaking stones, I
wasn’t paying enough attention to something. I needed to slow down
and look at everything, several times, before pushing down, or
running a file over anything. Even fragile stones don’t damage
themselves, it takes some outside force. The trick is to not be that
outside force.

It is much more likely that a stone will be damaged while cleaning
up around it after setting than during setting. There are also
accidents that damage stones like slipping with a tool, dropping it
on a steel tool in the bench pan, not paying attention while doing
work near a stone and hitting it, scratching the table by leaving it
table-down on the bench or even absent-mindedly quenching a hot ring.
But in all of these cases damage is preventable, if enough care is
taken. Every stone I have ever damaged was because I didn’t pay
enough attention to the details. Not one ever chipped, cleaved,
scratched or shattered itself without my personal intervention.

I now put a towel in my bench pan and keep all tools under it
whenever I handle a valuable stone, even if I’m just looking at it in
the paper. I use the back side of a clean, soft leather drink coaster
or a suede pad to set the stone down on instead of the top of my
bench, and I never - repeat - never set a stone other than a diamond,
table-down on anything harder or more abrasive than the skin on the
back of my hand without ensuring that the stone’s table and what I’m
setting it down on are both completely clean of everything, and there
is a darned good reason to do so. Even then I never, ever slide it.
Just picking up a stone that’s table down can provide enough sliding
pressure to gouge a deep scratch in it, even something as hard as
sapphire. These procedures are all due to lessons I have learned
from stones I have damaged - because I didn’t pay enough attention to
the details.

When bead setting, channel setting or pave’ing, touching a beading
tool or graver to a stone is the most likely cause of stone breakage,
uneven seats, touching girdles and the use of force to make an uneven
or poorly fitted seat work are probably second. Bead setting peridots
in 18K white gold makes the above reasons much more likely to cause
damage because 18K white takes a lot more pressure to move, peridots
take much less pressure to break and are much more easily scratched,
but it’s still all the same causes at work. You can also add in the
potential for damage done by pickle, heat, ultrasonic or steam to
peridot, but once again, these things are all preventable with a
little caution and forethought. A microscope helps too.

So I would love to hear people experience when setting. When do
you order extra stones for breakage? How many do you order when you

The answer to this depends entirely on the stone setter and the job
at hand. When I’m setting 1/4 cts, I don’t order any more than I
need. If I break one, I’m upside down in the job big-time, so I “just
don’t break them”. Channel setting princess cuts, I order an extra
stone or two, but primarily to provide a variety of stones to work
with; even the best princess cuts are rarely perfectly square or
perfectly matched in their dimensions. Every now and then I’ll see
that little white corner on one and I’m really glad I’ve got that
extra stone or two. If I’m setting 1.5mm peridots in 18K white gold,
I order a whole bunch extra, because I know that I’m going to break
a few, but the matching thing is usually more of a problem. I could
probably take the time and not break as many, but the extra time it
would take would take my profit out of the job, 1.5mm peridots are
cheaper than my time (I usually mutter something like “That stone
didn’t match anyway” as I chuck it in the trash). Sometimes it’s
exactly the opposite, I’m working with a customer’s gramma’s
diamonds, and there just aren’t any extra. Then the option to proceed
with speed is not there, so I “just don’t break them” and charge for
my time accordingly.

Of course that’s not entirely true, it is not possible to “just not
break any stones”. We are all human beings after all, and nothing
touched by the hand of Man is perfect, so stones do get broken in
spite of my best efforts to the contrary. I will add that my
percentage of broken stones does seem to go up proportionally to the
number of extras on hand (and goes down proportionally as I use them
up), so there has to be at least a tiny bit of a psychological
component at work, for me anyway.

Learning to adopt the attitude that “it is flat out not an option to
break this stone”, treating every stone as though it’s as soft as
apatite, as fragile as heavily included emerald and as valuable as
fine Burmese ruby, and then doing whatever it takes to set it and
finish the piece without damaging it improved my odds by an
incredible margin, even if it did slow me down considerably at first.
Turning my frustration at a lack of speed into a fascination with the
pursuit of cutting the perfect seat was the key for me. I had to make
that extra fifty or a hundred cut-and-fits my friend. An extra hour
or two’s worth of labor is far cheaper (and a lot easier on sleep
patterns and the ol’ heart rate) than cleaving the corner off of a 5
carat emerald, or even chipping a quarter carat diamond so it is
almost always time well spent, even when I can’t charge for it.

At any rate, at this point in my career I tend to lose at least as
many stones as I break and lose at least as much time looking for the
darned things as I’ve lost to slowing down and learning to enjoy the
process. Usually. Sometimes?

Dave Phelps

I would like to add to my rather long post, if I may.

It is much more likely that a stone will be damaged while cleaning
up around it after setting than during setting. 

There is a tendency to think “It’s tight, it’s straight, it’s level,
I’m in the home stretch now!” Nothing could be further from the
truth. The next ten or fifteen minutes are the most critical in the
whole job. One slip of a file, one look out the window while a
graver is in contact with a bezel right next to the girdle, one
stroke too many with a saw while cutting off a prong, and there’s no
sleep for our stone setter tonight. It’s tight, straight and level,
and it has a big ol’ goober on the crown.

Never let your guard down. The job isn’t done until the check clears

Dave Phelps

I am trying to get a handle on the average breakage of precious
and semi precious stones during the numerous setting procedures.
Ie. Prongs, burnish, pave', channel, etc. 

Wow! I want to see what you find out James!!!

The answer better be “0” !!! If you need to order extra stones to
cover breakage, you need to either learn to set or hire a setter!! We
set a lot of stones that belong to our customers… like yesterdays
17 ct cushion cut burma ruby… You’re not going to replace that
stone…nor are you going to “order a few extra”. For goodness sakes,
if you do re-manufacturing in your shop you’d go broke in a week!! Do
folks REALLY order extra stones because of breakage when
setting??? Good… but SCARY question James. I have to go get a
cup of coffee now… Just the thought makes me shake!!! :wink:


David, Thank you for your post, I enjoyed the read and you are so
right, the job should be done with the mindset of your friend. Sage

I am trying to take into account the reality or the skill, Good and
Bad. I have the start of a chart of breakage frequencies, and am
looking for more anecdotal evidence to be able to test against it. I
hope to collect enough real life data to model this loss of revenue
during the coming year.

If you or anyone for that matter wanted to keep track of your
breakage, stone loss, etc., at the bench I would really appreciate
the data and would return the collected upon completion
of my project.


If I am setting small stones (2mm and below), I will order an extra
stone because I don’t want to spend 2 hours looking for a dropped
$3.00 stone. Of course, I am talking about most colored stones and
low quality diamonds. This does not hold true with exotic stones like
Alexandrite. I don’t order extra stones because I am afraid of
breakage. Like anyone else that sets stones, I have chipped/broken
some stones, but that just goes with the territory…


1.3 mm citrines and peridot in a prong set channel band in 18KW We
break a few, I am mostly after the breakage on accent stones.


What is the objective, James? Are you a setter trying to figure your
losses or are you an employer trying to get a handle on what your
people are costing you?

Dave Phelps

Hi All

I have been a stone setter for 23 years and have worked on everything
imaginable from mass produced pieces right through to works worth
over one million dollars. Rings with 300pc pave to rings with over 10
carats of diamonds in the one piece

I regularly work on very large emeralds that most setters would
rather burn their own eye ballsout than even touch. I have very few
problems with broken stones. Usually the only time a stone is damaged
is because of poor planning by the designer or poor communication
between the maker and setter. If you have the skill and follow the
obvious rules you shouldn’t have too many issues. I used to get
pressured into setting stones in jewellery that never should have
been attempted. Example is channel setting aquamarines with a razor
sharp girdles into 14ct white gold. It can be done but your chances
of no breakages are low. If it has to be done you have the stones
recut with thicker girdles with no sharp edges Some retailers in
order to save money will insist on trying to fit a stone into setting
that is not designed to fit it or stones that are too brittle for the
metal alloy. They say "I know this ring was made to fit a shallow 4mm
stone but I have this deep 5mm stone, can we make it fit ?"That’s
when Booboo comes to visit.

Now If I think it shouldn’t be done I say so. Although it helps to
have more work than you need. I imagine setters that are not busy
are more likely to be willing to do things they’d rather not do.
Important factors in avoiding breakages are getting the correct
angles of claws or setting shapes depending on the stone shape or
type. Certain setting designs will put far more lateral pressure on
a stone girdle than others to get same stone tightness. Also hard
alloys like 14ct white or 9ct Rose gold have to be worked
differently than other metals. To tighten a claw setting you don’t
push the claw directly at the stone. The metal will only spring back
to where it was. You push the claw a little forward but mostly to the
side, then push it again a little forward but to the other side.
Anyone not clear on that email offline and I’ll try to send you a
diagram. other factors are having enough support under or between
stones and the right balance in weigh tor metal thickness. Having
very thick claws but a thin bezel will cause problems. etc etc etc
etc. I should write a book…

OK. LASTLY. This is my whole point…

If breakages are so common that you have to compile a study of its
occurrences then something is severely wrong. Any setter that is
having more than a few minor breakages each year is either being
pushed into doing things that they shouldn’t of else their methods
are lacking forethought.

Phil W

1.3 mm citrines and peridot in a prong set channel band in 18KW We
break a few, I am mostly after the breakage on accent stones. 

what is a “prong set channel band”? new one to me.

Do folks REALLY order extra stones because of breakage when
setting?????? Good..... but SCARY question James. I have to go get
a cup of coffee now.... Just the thought makes me shake!!! ;-) 

Common dude, I like to have a couple of spare small stones if I am
setting. 17 ct cushion cut burma rubies are difficult to break. .7mm
emeralds are easy to dustify…



1.3 mm citrines and peridot in a prong set channel band in 18KW We
break a few, I am mostly after the breakage on accent stones. 

it doesn’t matter about the stone size. If you are breaking stones
you are doing something wrong. Either rushing through a job or just
not preparing the setting. Mabey we look at it differently here…
but even with melee… prepare yourself and the mounting… don’t
break stones. Just think… each stone is an individual work of art
with part of someone’s life tied to it… Don’t waste it! Not saying
here that we never break a stone… we do. ;-( But certainly not
often enough to order extras because “We plan on snapping a couple!”
Just do it right.

Still a great question and I am enjoying the answers!!! Dan.

DeArmond Tool

Here we have the dichotomy of guys setting stones that cost a year’s
wage each, not understanding how the guy trying to channel set
$30/carat emerald melee in a worn walmart setting or prong setting
3X5 mm cruise-purchased marquise cut opals with end caps could ever
break a stone. Try to remember the FIRST 5,000 or 10,000 stones you
set, and what your success rate was then.

Lee Cornelius
Vegas Jewelers

OK James. I’m assuming you are a stone setter, trying to figure out
what are acceptable losses. I’m going to speak to you as one
professional stone setter to another, just as I was once spoken to
when I asked for advice concerning broken stones. I hate to be as
blunt as I’m going to be in this post, and avoided doing so in my
first post, but here goes.

I’m reminded of military leadership discussing “acceptable losses”.
To the grunt on the battlefield and the doctor in the local town
treating civilian casualties there is no such thing as “an acceptable
loss”. To the four star general and to the professional stone setter,
there shouldn’t be either.

Perhaps I was not clear enough, you seem to have missed my point. As
Phil and Jeff both suggested, and as I tried to say, don’t plan on
breaking stones - just don’t break them - period. If you really are
having enough loss due to stone breakage that you feel the need to
keep a chart of it, you are breaking far too many. As Dan says, “the
answer better be “0”!!!”.

A cavalier attitude towards stone breakage is totally unacceptable
in the trade. In my humble opinion, creating a chart to predict
losses due to stone breakage over the course of a year is a
demonstration of just such an attitude. If you want to be a
professional stone setter, you really need to change your thought

Rather than spending time trying to predict your losses to stone
breakage, your time and energy needs to be better focused on
preventing breakage in the first place. If you don’t get a handle on
it soon, and by soon I mean by the next time you chuck up a bur, you
may not be doing this for much longer.

hope to collect enough real life data to model this loss of
revenue during the coming year. 

Using Dan’s example, if you damage one 17ct Burmese ruby, your
revenue loss for the year and for a long time to come might have you
cutting lawns and delivering pizza for the rest of your life. This
is real life data for a professional stone setter.

You can’t chart the loss to your reputation or the number of future
jobs you won’t get by keeping track of broken stones, and that is
where the real loss of revenue will be. Think of a surgeon tracking
the loss of revenue to his practice based on the number of wrong
limbs amputated per year and you might get an idea of how you should
be approaching this subject.

Use each stone you damage as a learning experience, and never make
that same mistake again. This was the point I was trying to
illustrate, and maybe save you learning a lesson or two of your own
with damage prevention measures I have learned from my mistakes and
those of other setters I have worked with over the last thirty-plus

With the rare exception of jobs like pave’ing 1.5mm peridots in 18K
white gold you should never “count” on breaking stones, and even
then, the number of broken stones better not be more than a couple.
It is possible to do setting work to this standard, although it is
sometimes considered to be not worth the extra time. Such an
“acceptable loss” should be weighed against the time spent and should
be a rare exception to the rules, never just accepted as a normal
part of the business. Sorry if I gave the wrong impression using that
as an example before.

If they are a customer’s stones, even 1.5mm peridots going into 18K
white, consider them irreplaceable and do what you have to do to not
break any, even if that means turning the job down Because in the
eyes of most customers, that is exactly what they are, irreplaceable.
When such a loss is unavoidable or the risk is great as Phil
discussed, the customer must be consulted, and you may just have to
say no.

Sometimes not breaking a stone means not setting a stone. Your
professional reputation is at stake, even if the customer says “go
ahead anyway”. It’s just fine until you really do break a customer’s
stone. Then it’s not alright anymore, regardless of their previous
OK. “See? I told you so” just doesn’t cut it as a defense, and
certainly won’t do much to expand your business.

I recommend that you tear that chart up, delete the file and
consider taking a stone setting course. There are many very good ones
around, check the archives for recommendations. Then make it your
personal goal to not ever damage another single stone for the rest of
your life. This is the kind of goal a professional sets for himself.
Others that have posted have obviously adopted such a goal at some
point in their career, specifically Dan, Jeff and Phil. Every
professional stone setter I know worth their pay has as well.

Just because perfection is not humanly possible doesn’t mean you
shouldn’t strive for it. You sure aren’t going to get anywhere near
perfection without at least trying.

I’m not posting this to be contentious, or to put you down in any
way, James. I offer it only as a fellow professional that wants to
see you prosper. I made a promise once to help people achieve
success and avoid pitfalls that I know about, and that’s my objective
here. Please accept my constructive criticism in the spirit in which
I give it. My Mom would have called it “tough love”. My Drill
Sergeant would have called it “a little dose of reality” and then
would have told me to drop and give him twenty.

Dave Phelps

David, Lee, Dan, Hans, Tim, Phil, et. al.

Thank you for your contributions, I will explain a little better
what I am after, I am working on a model for automated stone ordering
for manufacturing and I am assuming a few things.

  1. That stones will sometimes be broken.

  2. That by having extras I can eliminate the loss of time required to
    source replacements, and the added shipping expense.

  3. That any extras can either be used later on, or grouped and
    returned to the supplier thus reducing return shipping fees.

All of this is really about the accent stones and those include
everything from diamond to emerald to peridot, from 1.3mm to 4mm in

My own experience with breakage is almost none, the last stone I
broke while setting was a paper thin Harlequin Pinfire Opal. I was
the only person in town who would attempt the job, I was young and
foolish. I replaced it, it took about a year to find a suitable stone
and then it has to be recut.

But I cannot say the same for everyone and if I need to order a few
extras because I don’t want to wait until another stone is supplied
to the offending setter, I will order them. Maybe hide them so they
don’t realize we have them, but have them just in case.

So far the discussion has been very interesting, and I understand the
sentiment. But I would love to get a set of numbers to use to test
the model, a starting point that is not just grabbed out of thin air.
I am sure somebody has an idea out there.

I have my idea, but it is one set of data and I am after more


When I was 20 or so I used to take all my settings to a guy, Jim,
who was probably the best setter in London. He had a workshop in
Hatton Garden up a rickety flight of stairs. He kept a pot of thick
coffee heating all day and the visit always ended with him pouring
me a treacly cup of the stuff and telling me why I was a terrible
designer and how I could make his life a lot easier.

O a freezing January day I went to see him with another of my
unworthy offerings and his door was shut. I went down the stairs to
his pal, a polisher, who told me that the day before Jim had a
magnificent topaz delivered for setting in platinum. He’d hardly
started to set when it snapped clean in two right across the table.
Jim put down his tools, left his workshop and never came back. He
sold the unit to a colleague.

I saw him later at a gemmological class that he was taking for a
friend and he said that as the stone snapped his heart raced at such
a pace, he felt nauseated and suddenly realized that he was under
more pressure than a tightrope walker, a soldier in a foxhole, a
refugee at a border. Worse that anything he’s felt in the German
prisoner of war camps.

Life, he said, was too short. He’s retired to grow alpines.

Tony Konrath F.G.A.

I think context is important here. What material, what style of
setting. If you have to set tiny princess emeralds in 18KW channels
you will get different results than a single large corundum center in
plat prongs. Big durable stones are tough to damage, little pointy
brittle stuff is not.

But the OP probably wants some numbers so while I never kept track
I’ll venture some off the cuff estimates

No Brainers… .practically zero except for days I left my brain at
home. Foolers… .maybe 5% due to being fooled that it was a no
brainer job. Ticklish… .quite variable but usually low because I’m
prepared for it. Customer Goods… three Hail Mary’s and I’m good to
go. Not infallible though.

Overall I suffer more loss from the dropsies than from breakage. I
have found that the best way to insure that I need extra stones is to
not order any. And the best way to not need the extra stones is to
order them! So what do you think I do?

To expect a learning jeweler to have zero loss is unrealistic. The
only way you’ll learn how much stress a given stone will take is to
break it. Then you know or at least your hands will know. Of course
we try not to tempt fate on expensive goods, but even if none will
admit it, more than likely most of the greybeards have clicked a
sapphire or two in their younger day. What’s important is how/if you
progress. If you’re having a problem with a particular set up, you
need to work on that.

“Just don’t break it”, if you’ll pardon me, doesn’t quite help. Nice
goal but more productive would be details on seat preparation,
tooling,… yadda, yadda. Identify the cause not just the result.
Sure, positive attitude is good, but you gain a positive attitude
thru previous success.

I will disagree about goldsmithing not being an ‘industrial process’
(sorry I’m losing track of threads). We’re not spreading oil on a
canvas, we are performing mechanical tasks whose results very much
depend on the process used, at least as far as execution goes,
design is something else. But of course it doesn’t have to be blind
industrial process.


Here we have the dichotomy of guys setting stones that cost a
year's wage each, not understanding how the guy trying to channel
set $30/carat emerald melee in a worn walmart setting or prong

When I started setting 35 years ago I knew very few if any of the
rules in setting stones. I read, studied and read some more. I knew
I wanted to be a jeweler. I felt and still feel that if you are
going to call yourself a jeweler…or a carpenter, or a computer
analyist… BE ONE! Be the best one there is! I’m not the best
jeweler or stone setter there is… "BUT IT AIN’T BECAUSE I DON’T
TRY!!! :wink:

35 years ago I bought (if I recall) about 100 of the worst grade
rhinestones I could find and a big handfull of heads. I soldered
those heads to a piece of copper plate and began to set…(yeah,
right)… stones. I think I broke 95% of those stones and ruined
probably every head. I ordered again. I broke more stones and ruined
more heads… but not as many as the first time. I ordered
again… and probably again. Thats how bad I wanted to be good at
what I do. I guarantee you, I can set 100 of the worst made most
awful cut rhinestones today and not break ONE! And… yep, I’ll pave
them if you want me to.

You just can’t do work for the public and have a goal of “Only
breaking a few” stones. If you are breaking stones, learn to set.
Spend the time & money or STOP! Folks won’t remember all those
stones you Didn’t break… but they danged sure will tell all their
friends about that ONE you DID! Its a pride thing I guess. If I
couldn’t have mastered the art, I wouldn’t have gone forward.

Setting is easy once you decide to prepare yourself and the
mounting. It’s no less than threading a 1" nut onto a bolt. When
everything is right, it just glides on. If something isn’t right, you
can’t force the nut onto the bolt… so back up, make it right and
enjoy the glide. I know there are those out there that just want the
dollar…go to the next job and get the next dollar. Thats ok I
suppose but I’d rather have a customer wait an extra day… or
two…or ten…and walk out with that smile you’ll always remember
on the way back to your bench. When I hand a customer a piece of
jewelry I always look at their face… not what I’m handing them.
That look is as much my pay as the dollar. Nope, can’t eat it, can’t
pay bills with it… But I can danged sure sleep with it! Just do it

DeArmond Tool