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Burnt diamonds!

#1

First I would like to say how enjoyable the “Benchexchange Page” is,
suddenly felt at home all around the world, had to rush of to get my
partner and show her how perfectly normal my untidy workshop is, may
even get round to adding my own to the page.

Now the problem, in the last few months I have burnt more diamonds
than the previous 30 years and cannot work out why, no I’m not going
senile, its only on 18ct yellow jobs that need retipping, also seems
more like a stain, as you can imagine this is becoming expensive.Has
anyone got any ideas as to what is causing this. Many thanks Roger

#2 
in the last few months I have burnt more diamonds than the previous
30 years and cannot work out why

Either the stones aren’t clean enough, in which case you need to
check your cleaning equipment and perhaps change as needed whatever
may not be working right,

or,

your not protecting them adaquately, which might be due to
old/dirty/contaminated boric acid / alcohol slurry, or whatever
you’re using. It’s cheap, so to be on the same side, toss what you’re
using and mix up some fresh… Be sure there’s enough boric acid
powder in there…

or,

Your getting them hotter than you used to, without realizing it.
did you change to a different melting point solder? different
refiner? Or have you changed to a different fuel or torch setup? Or
has your shop lighting changed so you can’t see the temperature
correctly?

or,

You’re taking in work someone else has already burnt, and not
noticing it till after you’ve worked on it?

Or… ?

Hope that rings a bell somewhere…
Peter

#3 
    Now the problem, in the last few months I have burnt more
diamonds than the previous 30 years and cannot work out why.

Many folks don’t realise that there is a difference in Boric acid
and borax. Have used boric acid with all my retipping, (after a
thourough cleaning of stones)!. Just saw a tip to clean stones, by
rubbing them in you palm with table salt! Tip states salt has a
hardness of 2.5 and will not hurt stones above that hardness. Any one
try this? Thomas

#4

Roger, you may be running into filled diamonds and the treatment is
burning out and leaving a burt residue or the inclusions are showing
up.I ran into this problem with a platinum ring I was sent to change
the head on. The melee had all been filled and turned a frosty white
all the way aroun the ring even though I was only soldering at one
spot and using 1000 degree solder. A possible explanation. Frank Goss

#5 
  Now the problem, in the last few months I have burnt more
diamonds than the previous 30 years and cannot work out why...

Hi Roger, It sounds like dirty diamonds to me. Chances are the
diamonds in these retipping jobs have been gathering dirt for years
and when you heat them the dirt is getting baked in. This is a
common phenomenon and I don’t think there’s a good way to remove the
discoloration short of repolishing. The fix is a preventative one:
Thoroughly clean the jewelry piece before doing the repair.

Beth

#6

Often the admonition to clean the jewelry well before retipping or
building up prongs is advised. The problem truly is, how to get it
truly clean. I have tried the very strong solutions made for “5
minute cleaning” and even this fails. Too often, even with much
steaming, much ultrasonic time, the crud is still there in just
enough quantity to cause a black looking stone.

I have found a solution to the problem “after the clean jewelry was
worked and the stones look dark.” This is only for jewelers with
good ventilation and an experience with heat control and recognition
of heat colors in the metals.

This is what I do when a “clean” ring, one of those with tiny holes
or none at all behind the diamonds shows burnt dirt on the stone
after torch work: Flood the surface and backs(if holes exist) with
Handyflux, the stuff with flourides and ventilation needed. Heat
gently, the flux will try to escape the holes and you will need to
prod it a bit under heat and add more. When the flux acutally gets
into contact with the stones, properly controlled heat will allow
the “cleaning properties” of this flux to go to work. The black
residue will be removed. This extreme process works extremely well
but you have to know heat colors to use it or risk damage to the
jewelry.

I report about 100% success using Handyflux or a smilar brand of
brazing self-cleaning flux in cleaning diamonds with burnt-on dirt.
Sure, the pickle takes longer to remove the flux but the item is
clean and the stones shine without the black coloration. Has anyone
else tried or used this technique? Let me know of a better way if
you have one. thanks.

Thomas, professional bench jeweler.

#7 
Has anyone else tried or used this technique?  Let me know of a
better way if  you have one. thanks.

Thomas, I’ve generally not needed the flux trick to get off burned
on dirt, per se, since I’ve not often had the problem of not being
able to get a stone clean enough except for those types, with no hole
behind a burnished in/flush set, where there’s no way for flux to get
behind the stone either. But, i’ve found this VERY useful in
conjunction with laser welding, when you sometimes get a good deal of
black “smoke”, from recondensed vaporized metal from the welding
process, coating nearby things, sometimes in areas you cann’t reach.
Sometimes an hour or two in the ultrasonic still doesn’t get it off,
but the flux sure does. I don’t use Handy flux. Just lots and lots
(repeated applications) of batterns. You don’t risk it burning away
as much, so the stones remain protectede better, I think. But if
this has worked for the black smoke from welding, I see no reason why
it wouldn’t also be generally useful for your cases as well, as
you’ve found. The only trouble with your use is that sometimes,
since the stones also got hot enough to carbonize that dirt, the
stones too will be damaged, with a lesser polish or even bits and
pieces of the surfaces having become etched or frosted. No cleaning,
of course, can fix that.

One other trick you might try, either before your drastic means are
needed, just to also get the dirt off first, or afterwards, to get
the black off, is oven cleaner. We use the spray on type, with LOTS
of ventilation (It’s mostly straight lye, with some surfactants
added, I think, so this is nasty stuff). Spray the ring, and enough
into a small container to then immerse the ring, and let THAT soak
for a while. Then try your ultrasonic and steam again…

Peter

#8 
One other trick you might try, either before your drastic means
are needed, just to also get the dirt off first, or afterwards, to
get the black off, is oven cleaner

I had more than one occasion when my store was open to repair hollow
chains. After the first caught fire, and really smoked it up, I
would put them in the ultrasonic for hours prior to doing the
repair, but every now and then one would go up in flames again.
After reading this thread, I wonder if the oven cleaner would have
saved me hours of clean up work on the chains? Not that I ever
intend to repair another.

Don

#9

Another way to clean this black (carbon) deposit is to soak the
piece in hot sulfuric acid in the ultrasonic. This will clean
everything from the diamonds. Care should be taken to use gloves and
good ventilation and use common sense about the settings. I only use
this method with 14k or better and Plat. settings.

#10 
    Often the admonition to clean the jewelry well before
retipping or building up prongs is advised.  The problem truly is,
how to get it truly clean

We used to clean diamond jewelry in hot lye solution under an
exhaust hood before doing any retipping work. After a soak in hot
lye, the piece was ultrasonically cleaned and thoroughly steamed. We
checked with a loupe to look for any dirt or oil. If it wasn’t
clean, it went back into the lye solution, etc.

HTH,
Donna

#11

We clean most gems with tenacious gunk on them prior to soldering in
a lye solution (made from drain pipe cleaner and water) Not harmful
to crystaline gems or gold but removes the most awful stuff. Be sure
to add the lye in small amounts to the water instead of visa-versa as
the chemical reaction can be powerful. G

Gary Dawson
Goldworks Jewelry Art Studio
Quality and Integrity...Always!
@Gary_Dawson1
#12

Having a customer storming into my store ranting that I had switched
a stone, due to organic debris that did not get removed by ultrasonic
or steaming, carbonizing on the back led me to the discovery of lye
with will eat all organic matter. It works after the dirt is
carbonized as well. Just leave it in over night. Richard
in Denver

#13

As a bench jeweler for over 35 years, I have a bit of experience at
burning diamonds. Fortunately, I made all the mistakes early on and
now feel quite confident with retipping and casting diamonds in place
with no problems.

I think people are confusing burning diamonds with cooking organic
matter on the back of their stones because things were not clean
before you either cast or did soldering operations. I will share a
secret with you, it’s called “Drano”. That’s right, the stuff that
uncloges your drains. I have been using it for over ten years. Just
put a little in hot water in a beaker in your ultrasonic and within a
few minutes, everything that has been accumulated under stones will be
dissolver. I do mostly diamond work, but have used it on other stones
as well. I’m not sure if it would have an effect on turquoise or
pearls, but for me, I couldn’t do my work without it.

Hope this will help…Richard Olson, OlsonDesign

#14

Hi Gang,

Another solution for cleaning jewelery, especially rings, is a
solution of lye (caustic soda), sodium hydroxide.

Since most of the gunk that’s apt to be encrusted around the stones
on a ring is composed of soaps, creams & dead skin. a soak in a
solution of warm water & caustic soda works well to loosen the gunk.
Caution is in order when using caustic soda, it will burn exposed
flesh. Besure to rinse the item off under running water after
removing it from the caustic soda solution.

When you’re done using the solution to clean the jewelery, just pour
it down the drain. Caustic soda (sodium hydroxide) is the active
ingredient in many drain cleaners.

Dave

#15

Hi Thomas;

Yes, I’ve done something similar, only I used a thick mixture of
boric acid and alcohol. I heat the article to what I think must be
around 600-700 degrees Fahrenheit. It’s the point at which the boric
acid starts to become molten. Then I let it air cool, then soak in
the pickle for a while. Sometimes you have to repeat the process
several times. Careful when you are working with channel set
baguettes or princess cuts. When the metal expands, they can shift
around and when the metal cools and contracts, it can damage a stone,
either by pressing down on a point or sharp girdle, or by pressing
the edge of one stone against another. When I need to get jewelry
articles really clean before working on them, I put them in a small
stainless steel sauce pan I keep at a low simmering boil on a
hotplate. It contains about 2 cups of water and a couple teaspoons
of trisodium phosphate, which I obtain from stores that sell house
paints and supplies (it’s used to clean walls, inside and out, before
painting). The boiling solution works wonders on caked on gunk.
Whenever I have to repair hollow rope chains, I let them cook in the
stuff for a long time. Then they are subjected to the ultrasonic on
top of that.

David L. Huffman

#16

I reheat the stones until the dirt is carbonized and quench. This
removes it. I also take an empty v-8 juice bottle that fits nicely
in my gemoro ultrasonic and put acetone in the bottom of it. Just
enough to cover the piece. The bottle rests on the edge of the
cleaner and spins. I leave the lid off and it cleans most things up
really well.

Regards J Morley Coyote Ridge Studio

#17 
 I reheat the stones until the dirt is carbonized and quench.

did I read this right? Your heating your diamond set jewelery hot
enough to carbonize the dirt and then you’re quenching it? What
percentage of your diamonds break with this torture? While flawless
or near flawless diamonds without internal stresses probably can
withstand quenching, it’s pretty much a "very not recommended"
process for most diamonds…

Peter