This is an interesting topic. I fear I may have burned the diamond in
my engagement ring recently. I have an illness where I have to take
oral steroids and as such have gained a lot of weight over the last
year or so. I could no longer wear my wedding or engagement ring
which I was very upset about, so I used my ring stretcher and
successfully stretched my wedding ring. However, when it came to my
engagement ring, I may have burned the diamond when heating it prior
to stretching as it now looks very different to how it did before.
I’d read that you could solder with diamonds in place so thought it
wouldn’t do any harm. Incidentally I also snapped the shank as I’d
forgotten that we’d had it made smaller the day after my husband
proposed to me, so it had a weak spot! You can tell I’m new to all
this can’t you?! But I’m learning the hard way.
I solder with diamonds as a matter of routine. 1000's of times -
retipping, preset bezels, preset channel strips - all sorts of
things. It's common practice. They do require a boric acid/
methanol dip or you'll burn them. Otherwise, solder away...
Thank you John for a little sanity in this thread.
I can understand emotional reaction to taking a torch to expensive
gem, but there is no scientific basis for those fears.
Diamonds can burn if heated in presence of oxygen, that is why they
need boric acid coating, but as far as withstanding high temperature,
the melting point of diamonds exceeds 3500 Celsius. Diamonds do not
contain 2-phase inclusions which can make soldering dangerous, and
diamonds have near perfect thermal conductivity. Exception should be
made in case of fracture-filled and treated diamonds, but that is a
different story.
Yes, you are. Diamonds do not need to reach melting point to be
burned on the surface. I have seen this happen any number of times
and done it a few times myself. Repolishing the surface will usually
remove the burned area without too much weight loss. Diamonds can
absolutely be damaged with a torch, as can ALL stones. The idea that
red, white and blue stones are heat resistant has become an old
wive’s tale and is, quite literally like playing with fire in today’s
marketplace. Rubies in particular are so commonly filled with glass
that any heating leads to changes in their appearance. So many
treatments are on the market, many of them so new that no one even
understands them, that the risk of heating any stone is just too
great to take the chance. Sure if you have a couple of $10 sapphires
in a little ring it’s worth taking a chance rather than removing
them, but that’s about it.
Daniel R. Spirer, G.G.
Daniel R. Spirer Jewelers, LLC
1780 Massachusetts Ave.
Cambridge, MA 02140
Interesting…I work with PMC as well as Silver and Gold. Just don’t
put diamonds in any PMC Kiln and expect there to be stone/s when
finished firing!!! Had one student who had a strip from an old ring -
put it in the PMC item she made - no stones when taken out of the
kiln!
Diamonds can burn if heated in presence of oxygen, that is why
they need boric acid coating
I’ve been soldering with (small) diamonds in place for years –
without using a boric acid coating – and never had a problem.
However, I always clean the diamonds thoroughly before soldering. I
thought it was the combination of dirt and heat which caused a
diamond to burn, not oxygen and heat. In fact, I’d guess that the
reason Helen’s diamond burned is because it was dirty.
I may have burned the diamond when heating it prior to stretching
as it now looks very different to how it did before
That’s too bad, Helen. I’d suggest a good pickle, ultrasonic, steam,
all that stuff to be sure that it’s not just dirt, but you’re the one
who can see it. Diamonds being pure carbon, which of course burns
quite easily in air, it does need a coating of boric acid. Flux is a
mixture that behaves much like an alloy - the borax melts at a lower
heat, and the boric acid melts considerably higher, that’s why it’s
used as a protective coating. Anyway. My suggestion to Jesse Hyu was
to preset a diamond bezel and then solder it into the ring. That lets
you set the bezel all the way down to the edge - you don’t need to
have a bezel rim for setting. I used to make a ring that had a strip
of diamonds going under the center stone, all surrounded by 18kt. -
almost impossible to set in place, but easy to do by setting the
strip first. Many times you’ll have a delicate piece that can’t
handle the pressures of setting - without shellac maybe, or even
maybe not. Presetting the stone again is the answer. Anything
resembling a shadow box, too. That’s not to mention retipping,
strapping, and using solder to tighten stones in various ways. If you
have a princess cut diamond in a channel that’s the same size as the
stone, the diamond can just slide out the side. You can just put
little bits of gold under each corner to prevent that - neatly, of
course. There is one place to be especially careful, though, and
that’s pointed stones. If you solder on trillions and the points are
embedded in metal, you can pull the piece out of the pickle with
broken stones not from the heat per se but from the contraction of
the metal as it cools. Same with pears and marquises, and also
diamonds touching each other, like channel set baguettes or princess
cuts. Also they must be surgically clean - I used to burn baguettes
occasionally and I wondered why until I realized I layed them out on
masking tape, and didn’t clean off the glue. And there can be no
trace of shellac - if you get the sweet smell of shellac, stop
immediately and clean more. One time I retipped a diamond of about 6
carats, and the foreman was on my back to get it done, do I dunked it
in the pickle pot at about 1000F - he didn’t bother me any more after
that. Theoretically, according to GIA, you can heat diamonds to red
heat and quench them in liquid nitrogen, because of the thermal
expansion properties. I wouldn’t recommend it, though, just for piece
of mind. Very occasionally we’ll have some mishap with soldering
diamonds, but not very often, and certainly not with large stones -
it’s the little ones that get you, because they take up heat so fast.
We also melt the prongs on a setting and stuff occasionally - it
happens.
Diamonds do not need to reach melting point to be burned on the
surface. I have seen this happen any number of times and done it a
few times myself. Repolishing the surface will usually remove the
burned area without too much weight loss.
I believe I mentioned boric acid coating. If diamonds given a coat of
boric acid, and temperature is below melting point, than how could it
be possible for any damage to occur? Now I am totally lost ! What
would
be the mechanism by which the diamond can be damaged?
I thought it was the combination of dirt and heat which caused a
diamond to burn, not oxygen and heat.
You are correct about dirt, you are wrong about oxygen. You did have
a problem, but the problem too small to notice. Diamond will
completely burn in the presence of oxygen, but it does not happen
right away and it is hard to see on small stones. Large gems are
something else.
I thought it was the combination of dirt and heat which caused a
diamond to burn, not oxygen and heat. In fact, I'd guess that the
reason Helen's diamond burned is because it was dirty. So what's
the bottom line here?
Diamond is carbon, carbon + oxygen at elevated temperature = carbon
monoxide and carbon dioxide gas and no more diamond. Now it takes a
high temperature and a bit of time but they do burn. Boric acid flux
glass forms a protective coating to keep them from burning,but at
too high a temperature or too long at temperature the boric acid
becomes overloaded with oxygen and the diamond will burn. "Dirt"can
have compounds in it that reduce the temperature for the carbon
oxygen reaction and increase the likelihood of burning the stone or
may fuse to the surface of the stone and only be removable by
polishing off the crud. I believe if you were to examine the stones
that you have soldered without the benefit of a boric acid flux and
look carefully before and after heating you would see some
degradation in the polish of the stone. If the time of heating is
short enough then the damage may be difficult to see but it is likely
there is some.
Jim
James Binnion @James_Binnion
James Binnion Metal Arts
You are not likely to burn diamonds covered with boric acid when
soldering with gold or silver solder. It will probably happen when
soldering with platinum solder. What often happens is the diamonds
are not clean, even after a day in the ultrasonic. Then the dirt gets
burned on. You must clean completely before soldering. When this is
the case, we use lye to clean off all the organic soils, which we
affectionately call “customer slime” We just buy granulated drain
cleaner (not the liquid kind) from the hardware store. Be sure that
it is pure Sodium Hydroxide. Some drain cleaners also have some metal
flakes in them. Put about a teaspoon of this in a small beaker with
an inch or less of water. Float it on top of your ultrasonic solution
(we have a plate on top with a hole in it) and run the ultrasonic for
a half hour or more if necesary. I learned this technique many years
ago from the Baume Mercier Watch Co. I was having trouble cleaning
solid gold mesh watch bands before soldering them. They did it by
boiling in an enamel or glass dish for a couple hours, but we have
found the ultrasonic does the job well. Don’t try this on pearl
rings, or other delicate stones. Sodium hydroxide will also eat skin
and eyes, so be careful.
There is of course risk in practically every step at the bench, but
as a general rule it is safe to gold solder on diamond, sapphire or
ruby. You always need to examine any stone for internal flaws before
proceeding, just as you would if you were setting or resetting. As a
craftsman doing general jewelry repairs for over 30 years I have
regularly done prong repairs without removing these stones, when I
have determined that there is minimal risk. Now that I do my prong
work on the laser most often this is even less of a concern.
While boric acid is helpful and a reasonable preventative it is not a
guarantee against burning a diamond. If it doesn’t coat the entire
diamond (which it often can’t when the stone is in a setting) or the
heat burns off too much of it the chance of burning a diamond is
still there. On top of this is the fact that there are so many
treated diamonds out there today as well. You can burn fillers out
when you heat the stone as well. It’s just better not to risk it
anymore unless there is absolutely no other way to do the repair.
Daniel R. Spirer, G.G.
Daniel R. Spirer Jewelers, LLC
1780 Massachusetts Ave.
Cambridge, MA 02140
Borax protects not only the diamond (which can take heat) but keeps
the metal from burning. That’s why. If the HOLE where the diamond
sits gets burned, the diamond is OK but it reflects the burned metal.
Use Borax
Do NOT use borax on sapphires for retipping. Borax can etch
sapphire.
You are absolutely correct, but original question had a presumption
of correctly preparing diamonds for soldering. There are many ways to
hurt the diamonds while soldering, but that does not mean that there
is no way to solder them safely.
There is just one thing about soldering with certain stones in
place. While it is alright, in fact, recommended that one cover a
diamond with flux…never cover a corundum (sapphire or ruby). The
flux will burn into the stones’ surface and ruin it.
Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry!
Baking soda works better then Lye and is not dangerous. Boil rapidly
for 10 min. or so. I work for three stores and have been using this
method for years. It works.
You are absolutely correct, but original question had a
presumption of correctly preparing diamonds for soldering.
I have heard of sodium cyanide being used to clean up the burnt on
junk from soldering, have any of you used cyanide for this purpose? I
know this is “old school” technique but was wondering what you think
of this for practical and safety reasons.
used cyanide for this purpose? I know this is "old school"
technique but was wondering what you think of this for practical
and safety reasons.
This likely refers to bombing, which no responsible person will post
the details of, I hope. It’s very effective, yes, but to use the word
safety in the same sentence is humorous. They call it bombing for a
reason. But yes, it’s a very effective stripping procedure. Anything
I’ve ever seen relating to diamonds will come off in pickle, though,
or else the stone is truly damaged, in which case bombing won’t help
either.
I have heard of sodium cyanide being used to clean up the burnt on
junk from soldering, have any of you used cyanide for this
purpose? I know this is "old school" technique but was wondering
what you think of this for practical and safety reasons.
Please, Tara, do not even consider using cyanide. It works great but
the side effects are deadly.
When I was young and stupid, we used to do a process called
“bombing” in which cyanide was dissolved in water in an old cooking
pot, rough castings were put in the solution, a small amount of
hydrogen peroxide was added, and the top was then put on the pot. You
waited about thirty seconds or so and the cyanide would start to
fizz, and finally would pop when the reaction with the peroxide
peaked. The castings would come out clean and slick as a whistle.
This is EXTREMELY HAZARDOUS! I firmly do not recommend even
contemplating this procedure. I found this out when a jeweler in the
area I lived in (Dallas, TX) died of cyanide poisoning after placing
a small container of chocolate milk on the counter where he mixed the
cyanide solution. It had been wiped off and dried, but there was
still enough cyanide there to make it’s way through the paper
container and into the milk. He died on the floor of his shop before
the paramedics even got there. Very scary stuff.
There is also the environmental concern of disposing of your used
cyanide solutions. You can’t just dump this stuff into the street. It
will cost you a fortune to get rid of it. This I know from experience
as well. It is extremely hazardous and can contaminate our drinking
water, or just about anything else.
Please, please, please, don’t mess around with cyanide!
Hi Helen, I meant to respond right away about your diamond, but
goofed. Has It been resolved? Quite often, a stone is not burned at
all; dirt is just burned onto it. A burned diamond is very white with
a frosted surface. It must be pulled and given to a diamond cutter
for repolishing. This actually removes very little weight. It isn’t
ruined by any means. If the diamond has a brownish burned look to it,
it is not burned at all. Clean the piece the best you can. Dry any
water off it.Dip the ring in boric acid, borax and alcohol and then
burn the alcohol off. Now, heat the diamond as hot as you can without
getting it hot enough for the retipping solder to flow. As you watch,
the anti- oxidising material will cause the brown stain to magically
disappear. Let it cool slowly and then pickle it out and your diamond
will be as good as new. I’ve been repairing jewellery for so many
years now that I’ve had to do this many times and it has never gone
wrong. It usually happens from trying to rush a job thru the shop
without getting it good and clean first. Anyway, be of good cheer and
let me know how everything works out.