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Heating princess diamonds?


#1

hi, i’ve got a pair of 50pt princess cut diamond earrings that i need
to convert into a pendant. im always overly cautious when heating
diamonds and only usually risk smaller stones. did i read somewhere
to avoid heating princess cuts because of the weak corners or am i
making excuses for myself

thanks


#2

The issue around diamonds is surface to volume ratio. Simply, if
there is a large table, for instance, a baguette, the possibility of
heat dam= age when using hard solders increases. Princess cuts tend
to have large tables. Now, diamonds do take considerable heat, they
can with stand the temps. of gold soldering but won’t take the heat
of platinum soldering generally. It is possible to do soldering
around diamonds using plat. 1000 and plat. 1100 solder if you are
skilled at soldering and temp control. Above that and you will cook
the diamonds. It all depends on your distance to the stone from the
joint and your ability to control the heat so to not bring up the
temp of a stone to a critical point. To replace posts or bails on an
existing head with a diamond in the head, it is not an issue with
princess cuts that are 1/2 carat and using gold solder. But too risky
with paltinum solder. What I would do is warm them up and apply
batterns self pickling flux, cook it off then apply another layer
and cook off to build up a borax shield. Next I would take a pair of
heavy needle nose pliers (more on the idea of electrician’s weight)
and bend a set of self locking tweezers so one side lies flat across
the table of the diamond but not too strong, just to hold. Now you
have a bit of a heat sink with the steel on the diamond.

Then I would heat up the head evenly before I focussed the heat on
the solder joint. Any issue with a corner would be from quickly
heating up one prong and the expansion of that prong might put some
stress on the corner tip.

If the corners were properly set and the inside of the prong was
drilled correctly so the tips “floated” in the drill hole in the
center of the bearing, there would be no issue. I have never had
this happen to me over thirty years of fabricating and repair. Then
I would solder on new posts or a bail on the head with easy solder.
You will be fine. I do it all the time. If you are curious as to who
I am or my skill to be able to say all this, here is a link to the
diversity of what I do. All are hand fabricated except the platinum
ring with the two ruby cabs.

http://www.valeriesgalleries.com/conley.html
http://tinyurl.com/39x97e8

Good luck.
JtheJ


#3

My experience is that the reverse is true, smaller stones are
riskier, at least in propensity to toast. Its pretty hard to burn a
larger diamond if you take proper care. Although if you do it costs
more for sure.

A half carat should be no problem, just clean the hell out of it
first. Lye would be my choice. I have no compunction about retipping
with 20KWW, which is pretty darned hot. For earrings/pendant medium
should give you plenty of wiggle room.

Corners…well you have to judge the previous setting job. If it
looks like the stone was muscled in, yeah be wary. Not so much
because of heat, but the corners may have been stressed just shy of
disaster.


#4

My 35 years of experience working with 1/2 points up to stones worth
over $150,000.00 and more. 7 carat hight quality diamonds, rare
colored stones that you would have to morgage your home for if you
made a mistake. larger stones with greater surface areas pose more
risk then small stones that you can bury in borax. I guess the
bottom line is… if you are uncomforatble… don’t do it. You have
to be able to trust your ability AND your knowledge and experience.
AND, don’t raise the risk, simply use easy solder… it’s plenty
strong enough.

James F. Conley


#5
Now you have a bit of a heat sink with the steel on the diamond. 

Both posts today are spot-on about the topic. I’ve heard something or
another of the above quote on and off, though. Yes, your diamond WILL
act as a heat sink and prevent your steel tweezers from getting hot,
though I don’t know why that would matter. A heat sink is something
that conducts heat faster than the base being soldered, so it "robs"
the heat and protects the job (like an electronic component, often)
Just about nothing conducts heat faster than diamond… In the
above quote, the ~diamond~ is the heat sink, not the tweezers.

One issue that hasn’t been mentioned is really just something to be
aware of. On stones with points that are set in certain ways,
sometimes the points will break from the pressure of the cooling
metal. If you have a marquis set into a massive setting and solder on
it, it can happen that it will come out of the pickle broken just
from the contraction of the metal on cooling. Kind of like a tree
breaking granite boulders - slow and inexorable. It’s not common,
it’s not something to be all nervous about, but it can happen. A
princess in a four prong setting should be fine, soldering on an
earring post…


#6

i don’t think heat by itself will effect the corner any different
than the rest of the stone. u should be more careful of applying
pressure to the corners (ie. as in setting the diamond).

ty isaac


#7

The tweezers are to absorb heat away from the diamond. Small diamonds
seam to react to heat more then larger ones but that is because they
will have more contact with metal then the larger diamonds. The issue
is evenness of heating through the material. Lets go to an extreme,
if you have a VERY large gem and it is in contact with heat and only
part of that gem is heated, then that gem had an uneven amount of
stress applied to that gem. Uneven heat stress can account for
building what you could call fault lines in the material. Like
unevenly annealed metal. On a larger scale, what happens when you
have a cold front and a warm front come together? The heat stress
line is the critical stress area of any material. I have over the
years talked to customer who are trying to understand the concept of
stress, mention the simple process of bending a coat hanger a few
times and the wire breaks. What happened. Essentially bending causes
stetching on the outside and compression on the inside. This activity
causes release of heat. Think about it. I can’t tell you, you have to
discover it for yourselves or you will not hear it!


#8
On stones with points that are set in certain ways, sometimes the
points will break from the pressure of the cooling metal. If you
have a marquis set into a massive setting and solder on it, it can
happen that it will come out of the pickle broken just from the
contraction of the metal on cooling. 

A little clarification on how this is possible may help. Diamond
expands less upon heating than does the gold, so while it’s all
heated to soldering temps, the diamond is loose in the "expanded"
setting. When everything cools, both will regain their original
dimensions. If the diamond remains in the same position as everything
cools, all is well. But if the diamond shifted even a little while
things were hot and the diamond was slightly loose, if it gets
caught there and cannot return to it’s original seated position as
the metal cools, then you can end up with a whole lot of pressure
being applied by the contracting metal because the points on the
stone are no longer in their seats.

The other situation that happens, and this may be even more common,
occurs mostly when retipping prongs on these stones. As noted above,
the head and prongs tend to expand more than the stone upon heating,
so any gaps between stone and metal in or near the seat become
larger. If the solder you are using to solder on new tips flows down
into the seat or that gap, then as the head cools, there is now less
space, and the nicely fitted seat no longer fits the point, being
now filled with solder. That, just as with the shifted stone, is a
recipe for disaster.

The first situation is avoided in part by simply not being too
aggressive and over heating the whole thing. Work where you need to,
not overly heating the whole assembly. Also, use enough boric acid
fire coat on the diamond. In addtion to providing protection against
burning the diamond, it also provides a bit of a fluid layer the
diamond floats in. As the setting expands, this tends to keep the
diamond from shifting too much out of position, and aids it in
regaining it’s proper position as the metal cools. Also, while
working, simply pay attention to the stone. If it shifts, you can see
it do so, and move it back if you need to before the metal cools down
again.

The second situation is avoided also by working “small”, to keep
thermal expansion of the whole setting to a minimum, so gaps don’t
open up. but mostly, it’s avoided by careful torch control and use
of the right amount of solder so you don’t have lots of extra solder
flowing where you don’t want it to. Even if the stone is not
initially damaged from solder flowing down into a seat, it can
increase the pressure of the setting, making it uneven and less
secure. That can increase the chances of the stone being
accidentally chipped at a later date, either by the customer, or some
subsequent unlucky jeweler.

Hope that helps.
Peter Rowe


#9
if you have a VERY large gem and it is in contact with heat and
only part of that gem is heated, then that gem had an uneven amount
of stress applied to that gem. Uneven heat stress can account for
building what you could call fault lines in the material. Like
unevenly annealed metal. 

This is sheer nonsense. Diamond is one of the best, if not the best,
heat conductors on planet Earth. You can heat it to white heat and
plunge it into liquid nitrogen and nothing will happen to it. The
thought that metal tweezers can create stress in diamonds by drawing
heat away is utterly ridiculous idea. As long as diamond protected
from contact with oxygen, you can heat it without worrying. One must
watch out for fracture filled stones. These can be damaged by flame.

Leonid Surpin
www.studioarete.com


#10

You miss understood, the tweezers are for drawing heat away from
small diamonds as an extra safe guard. I guess there was a miss
reading and miss understanding. Diamond is hard and went under great
stress and heat during formation BUT, they will still cook and look
ashen white if subjected to too much heat. The tweezers was just one
of different ways to draw some of the heat away during soldering
near a diamond with 19K weld or plat solders.

But with time and experience you will perhaps learn your own tricks.

But, hey go right ahead do that with a customers 5 carat $100,000.00
diamond. In fact, just to proove your commitment to your words, be
my guest… heat up someones quarter of a million dollar diamond till
it glows and then quench it. How about welding platinum, around the
diamond just to proove your point.

Here is an excerp from wikianswers, I just didn’t want to go to the
trouble of searching the GIA library to give you a quote-

“You can heat a diamond with a torch and place it in liquid oxygen
it will chemically transform into gases. One can also use a simple
device called a thermal lance. It will easily destroy a diamond.”

Site after site talks about destroying a diamond with heat over 1400
degrees. That is right in there with gold brazing alloys. I am only
try to help you, not argue. You need to re-educate yourself.

Good luck.
James F. Conley


#11

thanks for the responses.the job was successful, customer happy,
money in my pocket and confidence boosted!i guess i will always be
slightly nervous about heating stones but as someone on here once
said, “only heat stones you can afford to replace”.its surprising how
one bad beat as a trainee can stick in your mind when you come across
a similar job at a later date. 10 years later and now self employed,
its time for me to stop out sourcing my re-tipping jobs and accept
responsibility!

cheers, jon


#12
The tweezers are to absorb heat away from the diamond. 

Except that they don’t, and it doesn’t work like that. It’s
elementary physics. Any movement of electrons or radiation (as in
heat) will follow the path of least resistance. Fundamental stuff,
that. Heat will “flow” to the higher conductor, that’s what the
whole idea of a heat sink is about. In electonics, where they are
used extensively, you clamp a silver tweezer onto a diode and solder
it onto a circuit board, and the heat goes “into” the silver,
keeping the diode from burning.

So, Google “heat conductivity” and you’ll find everything. Clamp a
pair of steel tweezers on a silver ring, and the ~silver~ will act
as a heat sink for the tweezers - silver has a (much) higher
conductivity than steel, so that’s where the heat goes. It’s the
whole point. There is essentially ~no~ heat sink for diamond, as
it’s the highest conductor to begin with.

Higher heat conductive materials can behave as heat sinks for lower
conductivity materials, period, end of story.

This isn’t really directed at James, per se. He just said it again,
and I thought, “That’s it, I just can’t take anymore…”. Clamping
something onto something else does not a heat sink make - the clamp
MUST have a higher conductivity than the base part - it’s the entire
principle of the whole thing. People say it all the time, but they’re
just clamping stuff, not actually making heat sinks at all. It’s
irritating…


#13
This is sheer nonsense. Diamond is one of the best, if not the
best, Diamond is one of the best, if not the best, heat conductors
on planet Earth. You can heat it to white heat and plunge it into
liquid nitrogen and nothing will happen to it. 

I am afraid that you are wrong… again.

Heating diamonds to the temperature that you describe will cause
damage, irrespective of the presence of oxygen.

It is important to remember that when one makes statements like this
on a public list, those statements should be correct.

Please see,

http://www.meevis.com/jewelry-making-class-cooking-broken-diamond.htm

Cheers, Hans


#14
That can increase the chances of the stone being accidentally
chipped at a later date, either by the customer, or some subsequent
unlucky jeweler. 

Peter’s explanation is, as always, right on the button.

For myself, anything over a half carat diamond or a stone I cannot
replace, I unset it, fix the problem and then reset it.

These days there are too many treatments that can get you into
trouble when they are heated.

Just much easier to take the friggin’ thing out, fix the problem and
reset it.

Even though sometimes it adds to the work, like the second or third
claw breaks, it is still less of a mission than to have to explain to
the client that you trashed her stone.

I have done that twice in my 35 year career and I still dream about
it… it freaked me out that much.

Cheers, Hans


#15
The tweezers was just one of different ways to draw some of the
heat away during soldering near a diamond with 19K weld or plat
solders. 

Personally, I would not use 19k or plat solder close to a diamond.
And in 30 years of repair and custom,(no laser welder back then) I
have never used tweezers to protect a diamond. Alcohol and boric
acid do that. Learned that at G.I.A., 1977. Kind of hard to retip
prongs with tweezers on a diamond. Never frosted a diamond.

"You can heat a diamond with a torch and place it in liquid oxygen
it will chemically transform into gases. One can also use a simple
device called a thermal lance. It will easily destroy a diamond." 

Not quite sure what that’s about. Not quite relational to the
question about heating a princess diamond during repair. IMHO…

Richard Hart G.G.
Denver, Co.


#16
For myself, anything over a half carat diamond or a stone I cannot
replace, I unset it, fix the problem and then reset it. These days
there are too many treatments that can get you into trouble when
they are heated. Just much easier to take the friggin' thing out,
fix the problem and reset it. 

Just to keep thing on track, let’s recall that conversation started
as an abstract question “is it ok to heat a diamond”. Now it becoming
more about practice of diamond jewellery repair, which is quite
different conversation.

From that point of view - one should always unset any gemstone if
it possible. Soldering with gemstone in place should be the last
resort. It has nothing to do whether gemstone is valuable or not.
Client’s property is sacrosanct and should never be placed in
jeopardy, regardless of monetary value.

If treatment is even suspected and stone cannot be unset, repair
must be rejected unless client is appraised of the risk and gives go
ahead.

It is very important for a goldsmith to have proper attitude towards
Chinese say that beginning of wisdom is calling things by
their proper names. Gemstones have names and using "frigid thing"
instead of correct name, in my shop would be a reason for a
dismissal. It may appear minor, but it betrays of the attitude which
is very dangerous for someone to have, while working with valuable
material.

Leonid Surpin
www.studioarete.com


#17
I am afraid that you are wrong.. again. Heating diamonds to the
temperature that you describe will cause damage, irrespective of
the presence of oxygen. 

If diamonds do not have contact with oxygen, the only way to damage
it is to melt it. Diamonds melt at 3550 Celsius which is almost 6500
Fahrenheit. I do not remember recommending heating diamond to that
degree. Besides if you read carefully what I wrote, paying attention
to sentence structure, it would be obvious I was talking about rate
of change of temperature, which diamond can tolerate. Diamonds heat
conductivity is 2200 watts/ celsius. You need to ponder on this
number to appreciate it’s significance.

Leonid Surpin
www.studioarete.com


#18

Internet is a great resource, but when facts are important, I
recommend verification through conventional sources, like books.

"You can heat a diamond with a torch and place it in liquid oxygen
it will chemically transform into gases. One can also use a simple
device called a thermal lance. It will easily destroy a diamond."
Site after site talks about destroying a diamond with heat over
1400 degrees. That is right in there with gold brazing alloys. I am
only try to help you, not argue. You need to re-educate yourself. 

You have to forgive my lack of diplomatic skills, but the example
above is ridiculous. A lot of thing will be destroyed if they come in
contact with liquid oxygen when heated. Iron will burn as well, so
what does it prove?

Diamond burns down if heated to 850 degrees celsius ( 1562
Fahrenheit ), providing it is in contact with oxygen. While 1562
Fahrenheit seems to be low enough to be concern, in jewellery
practice, when diamond heated from one side only, it is not easy to
raise temperature of diamond to that degree. This is because
diamonds conduct heat very well, and unless surrounding area will be
heated to that degree, the threshold will not be reached.

All these experiments in diamond destruction are done with large
burners when diamond is completely surrounded by flame. In actual
practice is can only happen if someone would be using casting torch
to repair prongs.

Temperature of the flame is meaningless by itself. What is important
is the amount of heat and environment. But now we are getting into
area of soldering and heat management, and that subject has been
already discussed.

Leonid Surpin
www.studioarete.com


#19
This is sheer nonsense. Diamond is one of the best, if not the
best, Diamond is one of the best, if not the best, heat conductors
on planet Earth. You can heat it to white heat and plunge it into
liquid nitrogen and nothing will happen to it. 

OMG! Don’t anyone take this as gospel. What’s written is wrong, but
also

  1. Even if you only heat it up “half white” and plunge it, it has
    better than a 60% chance of cracking.

  2. Heating up a princess really hot and IF its set poorly, a tip
    will break off.

Treat princess cut diamonds like you would if emeralds could take
SOME heat.

David Geller


#20
i will always be slightly nervous about heating stones but as
someone on here once said, "only heat stones you can afford to
replace". 

Seems to be a job well done, Jon… I solder on a diamond each and
every day. Do the arithmetic and that comes to around 100,000 stones.
I’ve had a couple of problems but nothing huge and I won’t elaborate
on them. Meaning there’s really nothing to be afraid of, you just
have to learn (like everything else in life) how to do it and how to
treat them. It’s routine, and it’s routine in the industry. There are
many designs that ~require~ soldering on diamonds to execute the
design. Since diamonds can be heated, there are those who use that
property in the design process. Many here speak of it with more
caution than is really necessary, not having the confidence.

Why on Earth would someone weld platinum next to a 5 ct.
diamond?!?!?!?