I recently did a repair job soldering a post onto a piece that had
melee diamonds set into it. After cleaning the piece extremely
well, I boric acid the piece, did my soldering, let the piece air
cool, then put the piece in the pickle. Later, when I pulled the
piece out, the majority of the diamonds were black. I learned
afterward that the piece had some epoxy on it & assume that was
what had caused the diamonds to turn black. Does anyone know if
there is any solution to cleaning the black off the diamonds or if
I am going to have to remove & replace all the diamonds?
I recently did a repair job soldering a post onto a piece that had
The first thing I would try is powdered draino, I think the can says
red devil, and it is if you breath it, I do it on a hot plate
outside, 2-3 cups of water, 2 teaspoons of the powder, put your
piece in the solution , and boil it, 5 to 10 min., DO NOT BREATH THE
FUMES, this will clean everything off the stones, but I dont put
anything in this except diamonds. Its usually better to clean the
item in this manner before torching it.If that dos’nt do it, I would
coat the item well!!!, with boric acid and alcohol, and some more
Batterns green flux, 3-5 coatings, and then torch the piece gently,
with a slightly reducing flame, no more then 800 to 1000 degrees,
and then pickel the flux off. Diamonds are pretty tough when it
comes to heat, but if they are heated when dirty, the dirt will
actually burn into the surface of the stone, if that happens on a
smaller stone , I have found that I can clean off the ‘burn’ using
50 or 100,000 diamond grit on a new clean hard felt buff in my flex
shaft, you can see the burn using a loupe or microscope, so you can
also see when its removed, a burn like this is usually on the
pavillion facets so the stones need to be removed.Anything larger
than .15 to .25 is going to have to go to a cutter to be repolished.
When it comes to soldering first and formost its gotta be clean,
If the Diamonds had the glue or dirt burnt to the surface of the
stone you only have two options for those Diamonds. You will need to
remove the stones from the mountings and either boil them in Nitric
Acid or have them repolished.
Tough luck!!! Repairs will bite you in the butt so many times. In
the past, while working at a jewelery store, we occasionally “burned
diamonds”. You might try a solution of alum in water. We boiled the
pieces for a while. keeping an eye on the water level. Sometimes,
the burn will come off. Many times the crud goes away but there is a
cloud etched into the diamond. This can be polished off by a diamond
cutter. There is a great guy named Dirk Verbiest in Raleigh or
perhaps Durham NC who doesn’t charge too much to repolish and recut
Diamonds. Depends on the size etc. His business is called Diamant
This solution of alum will remove broken drill bits out of gold and
platinum as well. You might really check this piece over before you
stick it in the alum. Make sure there are no more surprizes in store
Good Luck , Dennis
when I pulled the piece out, the majority of the diamonds were black.
You’re lucky they are black. If they were frosty white, you might be
out of luck. If the piece can stand the heat, coat it with boric acid
and alcohol and toast it a bit to glaze the firecoat. Then darken the
room, or, as I do, heat the article under your bench above your tray.
When you can barely see a red color, stop and let it air cool. Then
pickle again, and let it soak in the ultrasonic a while. You may
have to repeat this several times, but it will eventually burn off
the carbon, which is what is left behind when the glue burns. If the
piece has low temp solders on it, and you are concerned about
dislodging solder joints, you can heat it just till the boric acid
melts a bit, then cool and pickle, and that will work, but it may
take many times. I don’t know of any acids that will attack carbon,
but I’ll be glad to hear from anybody who does. It’s possible that
if you leave it in the ultrasonic long enough, it will come clean
without any heating.
David L. Huffman
Hello “Manwithtorch” (I feel like I need to say that in a low,
I doubt the black you saw was due to epoxy - normally it’s just skin
oil, soap, the stuff your hands get into every day, which turns a
nasty black when you heat it enough. I recently repaired a ring with
2 large baguettes. I ultra-d the heck out of them, and steamed them,
but because there was no access to clean them mechanically
(toothbrush), there was still a very small film of “dirt”. Against my
better judgment (senior moment) I went ahead and repaired the ring
and sure enough I found a thin spotty black film afterwards. A couple
hours in the ultrasonic suspended in a baby food jar of pickle, the
one came clean after a litle additional steaming. But the other? I
tried everything I could think of. (Except for lye.) Ended up having
to call the customer to tell her I ended up doing: cut off the
narrower bar prong, removed the stone, rubbed off the dirt in a few
seconds, and repronged it. Clean diamonds really well, if you can,
before soldering because afterwards it’s a LOT more trouble. You
might want to try the hot pickle in a jar in the ultra trick, and you
might have luck if you can get to the back of the diamonds with a
toothbrush to help it along. Good luck.
Refined Designs Original Fine Jewelry
There is plenty of good advise about what to do after the fact -
it’s good to find that I’m not the only one polishing melee with
little wheels and diamond grit----. The real point, though, is that
you made a mistake. The mistake was, that when you take a torch to
diamonds, the very instant you smell burning stuff, and especially
the tell-tale smell of burning epoxy, you should stop, and reclean
the piece. If you do smell epoxy, then you know you have to do the
epoxy thing (Attack, etc.) I put diamond jewelry in the pickle pot
first - it cuts the grease way better than interminable
ultrasonic… Also a tip: At times I need to lay out stones on
tape - like a flair of baguettes that need to be in an order. I had
some burned diamonds that puzzled me until I realized it was the
glue from the tape - rinsing with acetone solves that.
Have any of you considered sand blasting. Even on loose diamonds,
rather than re polishing them.
P.F.F. Hinged ring Shanks
Sorry, I didn’t read the original post on this so I hope this helps
on the subject.
When it comes to cleaning off heavy dirt…burned in crud…Caustic
soda can’t be beat. Good ventilation, a tall pot, and a careful watch
while boiling will take out even the most suborn dirt safely. Rinse
and steam when done.
Proper tool for the proper job…
Ps Careful what stones you throw in there though. Pearls, coral,
turquoise & many others will not come out happy.
the best way to get the black off of a burnt diamond is to soak it
in a film canister that bobbles in the ultrasonic. the ultrasonic
needs to be hot. the canister needs to have 75% citris scent Mr.
Clean, and 25% clear Amonia (not the cloudy). if this does not seem
strong enough do a 50 / 50 mix instead. this method has never failed
for me. sometimes it needs to soak a couple of days.
I don't know of any acids that will attack carbon, but I'll be glad to hear from anybody who does.
I have used potassium hydroxide for years to remove carbon behind
diamonds that were cleaned with ultrasonic and steamer, and still
had dirt behind he stones. Especially small diamonds bead set, with
no hole behind the stones.
I get powdered pot. hydroxide from chemical supply in powder form,
mix with some water, and soak over night. Ultrasonic will make it
happen faster, but still overnight is best.
I had the same thing happen to me. Cleaned the ring really well, but
after soldering, the diamonds looked like they came out of a Baghdad
sand storm. Channel set smalls, too. No way I could unset and clean
without remaking the ring. So I took a chance. I heated them to a
DULL red and—wait for it—quenched them into cold battery acid
(dilute Sulphuric acid.) Admittedly, I did have replacement stones.
I did it about seven times and they came out looking brand new.
Whew! Not one was damaged. I figured that I had not much to lose; in
as much that unsetting channel set squares is a risky business at
best. And resetting them, even more so.
Two little factoids gave me the idea. One, when diamonds are cut it
is not unusual for the friction to heat them to a dull red. (a
diamond cutter told me that) and two, diamonds are often boiled in
sulphuric or nitric acid after they are mined. This is to remove a
natural yellow skin that is sometimes on the rough diamond, thus
raising the color and so the price per carat. This was told to me by
a miner of diamonds, many years ago, when I was still young, firm and
Cheers, Hans Meevis
The solution I have found works very well for glue or other dirt
burned onto diamonds is simply the flux called “Handy Flux”. This
stuff must be used with good ventilation in any case. To clean stones
that you thought were clean until the torch burnt the dirt giving you
"black diamonds", take the paste flux and apply with generosity to
the tops and especially the underseats of stones. Heat the jewelry
below red heat or solder flow temps, just enough to get the flux very
liquid. It is at this temp the “self cleaning” and long lasting
effects of “Handy Flux” may be appreciated. Apply more as needed with
a solder pic while hot since much fluz will tend to avoid the
recesses below stone settings. With enough flux and careful heat, the
liquid flux will clean it very well and throughly. Pickling takes a
bit longer since this flux hardens like a crust on the metal. The
stones will be clean!
Take care with retipped prongs, etc. The cleaning temp of the flux is
below most easy flow solder flow temps but good heat control is
certainly needed. If not totally comfortable with the torch, you
might try this on an item other than customer items.
Other than that, strong lye or oven cleaner does wonders to remove
dirt before soldering but not most synthetic cements.
God Bless, peace to all and best wishes.
Have any of you considered sand blasting. Even on loose diamonds, rather than re polishing them.
Allen this is an interesting idea. However, from my experience,
unfortunate as it is, when a diamond is burnt the surface is
etched. You could try and blast a diamond to see if it will get the
crud off. but if you have the crud off and it is burnt you are toast.
no pun intended.
The solution I have found works very well for glue or other dirt burned onto diamonds is simply the flux called "Handy Flux".
I thought to suggest that. You are right, Handy Flux will dissolve
stuff real well, and I often use it as you describe, but I refrained
from suggesting it because, as you’ve probably noticed, if you do
get a gold article hot with Handy Flux, when it reaches a certain
temperature, you get a lot of pink and black oxides on the piece,
and that can only be totally removed with abrasion. That’s a problem
with, say, channel set stones. Hydrogen peroxide and pickle will
remove some of it, but if the channel was polished, it won’t be when
Come to think of it, nobody has recommended electro-cleaning, which I
believe, uses a sodium hydroxide solution. There’s a product called
Tiva Clean, I think. It’s set up like plating, except the poles are
reversed. Use a stainless steel beaker or pan with the negative
hooked on it, the positive going to a wire which suspends the
article in the solution. I think I remember heating the juice to
around 120 degrees F. Anybody tried this with a goopy piece of
David L. Huffman
Hello Lizzie, boy I think that you are lucky!!! I caught that you
said that you pickled to remove the junk and flux from the piece. I
have done the same thing using boricacid and alcohol. Do you use
handy flux later when you are soldering on the prongs? It doesn’t
sound like it but I wasn’t sure. Just incase anyones gets the idea
that you can use handy flux when soldering diamonds please note, This
is really dangerous. We had a jeweler who brought that technique into
our store and burned, seriously burned, several large diamonds. We
spent a few hundred dollars getting them repolished. It was a very
delicate situation explaining to one of our customers why we were
sending her 2 carat oval diamond out to get repolished. I was taught
to use a solution of boric acid and alcohol as a flux when
soldering if there are stones in place. Apply only enought to get a
thin white coalt on the diamonds and still do not overheat this
solution. It too can burn a diamond. Who knows what other ingredients
are in hanyflux? I use it myself for general soldering, it is a great
product, expecially for silver. Interesting how many folks do so many
different things to diamonds.
Yes, I have used lye and oven cleaner with lye being very effective
removing organic stuff. Electrocleaning is also used with those
really tough to clean ones like rings with baguettes set with little
air below the stones. Dirt seems to gather and stay in the setting
ends on these stones and electrocleaning helps remove that dirt which
is in contact with metal.
The “handy flux” method I mentioned is a “last resort”, note: Last
Resort. I use this only when torch heat has burned some dirt onto
stones…dirt that stayed through all pre-cleanng and was not visible
until the heat got to it.
We have experienced no problems with burnt diamonds using this “last
resort” cleaning method. The oxide colors mentioned in another post
can be a problem.
I generally do not use handy flux for soldering but do use it for
neat clean flow around bezels and long sections of metal needing a
nice clean join. My soldering in general uses the basic liquid flux
with a precoat of boric acid/alcohol, of course.
I generally do not use handy flux for soldering but do use it for neat clean flow around bezels and long sections of metal needing a nice clean join. My soldering in general uses the basic liquid flux with a precoat of boric acid/alcohol, of course.
Why is it that people “generally do not use Handy Flux”? That is
what I learned to solder with in jewelry school. I do have to admit
that we mostly used copper and brass there. I think I only soldered
on sterling silver on one project - - but we still used the same
paste flux, Handy Flux.
Does it not protect from firescale?
Yes Nan, it does protect from firescale. However, the reason folks
are saying that they do not use it when soldering with stones ie.
Diamonds etc, in place, is that handyflux will damage the stones or
at least has the possibility of damaging the diamonds. Handyflux is a
great flux for the correct job.
handyflux will damage the stones or at least has the possibility of damaging the diamonds. Dennis
I’m going to make some of the chemists here wince with my pedestrian
understanding of the chemistry involved, but they can always clarify
if they so choose.
Part of what you say is correct. The borax in the flux will etch
corundum, that is, ruby and sapphire. But it is not true that it
will damage the diamonds. The only thing that will damage the
diamonds is excess heat in the presence of oxygen. And the damage to
the corundum is possible with most fluxes, not just Handy flux, as
most of these contain some form of borosilicate. The damage occurs
when prolonged heating allows the glass like material of the flux to
actually dissolve the corundum, since it’s basically a metallic
oxide, I believe, and these are soluble in glass. When diamonds are
damaged by heat, it is because some of the surface of the diamond
actually is burned away.
David L. Huffman