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Platinum problem

I am already into the christmas rush of custom work and this morning I
ran into a problem with a custom platinum ring guard. I do not work on
platinum much other then a sizing once in awhile over the years so I do
not consider myself extremely knowledgeable regarding platinum. I use
separate files and buffs and saw blades…platinum tripoli and green
rouge from Gesswein and platinum hard weld from Hoover and Strong.

Details: Customer wanted a diamond ring guard fabricated from her
diamond and platinum eternity band… straight baguettes 4x2 entire
circumference… O.K. so I ordered a 5mm platinum band half round from NOW
findings (They had a good price), cut the eternity band in half ( size 7)
cut the size seven platinum ring in half, welded the entire ring
together and used some platinum sizing stock for the cross braces to hold
the guard together…Job done… collect money happy me…and
then…good customer comes in and decides she wants the
guard two sizes larger… So I dutifully cut and weld in sizing stock …
surprise there is a line…a color line between the sizing stock and the
NOW finding platinum ring…a very slight color difference between the
two platinum pieces and a slight color difference in the welding Hoover
and Strong solder…I had no color difference between anything in the
initial fabrication…So I am searching for an answer…Any platinum
experts please take a moment a let me know what???

Terry Parresol in central Florida where it is still 90 degrees and humid

Hi, my name is Bob Martin All you should need to do is burnish
the seams with a tungsten burnisher and lightly buff afterward,
that should get rid of eney seam lines and eney pits as well,
good luck

Bob Martin
Hoff Jewelers
St. Paul, MN.

Terry: I’m no expert on platinum eather, but having been a bench
jeweler for over 20 years, I have learned an annoying fact. I
suspect what you are dealing with is a difference in alloy.
Stuller(and quite possibly Now) use a plat/cobalt combination
whereas Hoover & Strong uses the traditional plat/iridium comb.
Since you use H&S solder (as I do) I suspect you also use their
plat. stock. The two do not get along as I believe the iridium
is magnetic and as you point out, thier colors are different.
Don’t know why the need to change an industry standard which has
been in use for centuries, but…what do I know? Hope this


Whenever you are welding platinum, it is wise to use a piece of
the actual ring, roll it paper thin and wedge it inbetween the
seam. ( sometimes I even recommend a v-groove, so that you get a
weld all the way through). Then with your torch, using a very hot
oxidizing flame melt the thin part into a puddle all the way
around the ring. If you use a pt solder, be aware that they only
contain as much as 13% platinum, the ballance being palladium and
silver or some such. Palladium is grey and silver tarnishes, so
this will explain the line. The color difference could be that
NOW findings is using a different alloy than Hoover and
Strong…Just as 14k yellow gold may be different in color from
one vendor to the other, platinum alloys may also differ
slightly. Hope that helped…

For more technical please contact me at
Jurgen J. Maerz
Manager of Technical Education
JA Certified Master Bench Jeweler

   Don't know why the need to change an industry standard
which has been in use for centuries, but....what do I know? 

Platinum/cobalt alloys are a bit easier to cast, if you’ve the
appropriate equipment to handle them. Iridio/platinum alloys,
while wonderful for construction and fabrication, are devilishly
prone to shrinkage holes in sprues, various other forms of
porosity in a casting, and a truly monumentally large crystal
structure in castings. The platinum cobalt alloys give a finer
grain structure, and are slightly more fluid in casting, and help
to reduce the microporosity that can plague irido/platinum
alloys. also, for the record, iridio platinum alloys don’t
exactly have “centuries” behind them. Platinum itself started to
be used in only very limited experimental forms in the 18th
century, but was generally used pure then. And not until the
development of the oxygen/fuel torch in the late 19th century did
platinum come into general use in jewelry. That’s about a max of
one century, not more… Not sure when iridium entered use in
this picture, but I believe it to be the early 20th century.
Sometime around 1900-1910, I think.

It should be mentioned as well that iridio platinum is not at
all the only commonly used platinum alloy. 5% ruthenium is also
a common one that’s been used for a good while, often in
commercially available findings. And in europe and japan
especially, one can sometimes find platinum/copper alloys, as
well as a few others. Less common in the U.S…

And, if you want a real nice surprise, try soldering or welding
a seam in Steven Kretchmer’s new plat/SK alloy from Hoover and
Strong. It’s the one he developed to allow heat treating to
sufficient hardness to form the spring tension behind his tension
set rings. Nice alloy. And he’s gotton very good at doing
stunning and wonderful things with it. But if you don’t happen
to know that it melts about 500 degrees (F, I think, and the
number comes from a print article. Can’t verify it’s accuracy)
lower than 10% iridio platinum, and you go to, say, solder a seam
with 1700 solder, you’re in for a bit of a wake up, I think.
Steven, if you’re reading this, how 'bout some pointers as to how
best to handle your alloy?

Peter Rowe

Dear Steve; pardon me for disagreeing with a few of your points.
First of all it is the Pt/Cobalt alloy that is magnetic…not the
Iridium.Now Platinum alloys are made for a special purpose. Each
has its own function. Let me explain: In the early 1900’s the
alloy of choice in the United States was called Iridio/Platinum.
It was found that the use of 100 parts per 1000 of Iridium gave
Platinum many wonderful properties and it became the standard in
this country. It was good for machining, could be cast, could be
welded and could be fabricated. It did not oxidize and overall
had only positive features…except for one thing…In the rest of
the world, the minimum content of Platinum in an alloy was set at
950 parts per 1000. So in order to compete with the rest of the
world, in a booming platinum market, the US could not sell
900/1000 Iridium Platinum. So they looked at other alloys. There
was 950 Pt/Ru, but Ruthenium is very difficult to cast. Now for
machining it is fabulous. The Germans used 955/Pt/Cu a very nice
all-round alloy. The copper gives Pt the hardness and resilience,
without changing the color and for many years it was the work
horse alloy in Europe. In Japan 950 Pt/Palladium is used. It is
gray in color and needs to be rhodium plated to obtain the color
Platinum is famous for. Then Pt/Co came along. the Cobalt being a
grain refiner, it made the alloy more liquid and produced
superior castings. So for the past 2-3 years Pt/Co has been the
alloy of choice in Europe and it is catching on in the US also.
There is some resistance because of the slight oxidation and
ferro-magnetism, but overall, the benefit by far outweigh the
disadvantages. Meanwhile some casters thought they could beat the
system by casting in 950 Pt/Ir… the problem with that is that
the alloy only has a Vickers hardness of barely 80…so customers
will return the jewelry for it will scratch in no time and leave
the pieces looking worn… Using Pt/Co is not a bad thing. With
its hardness of 130 Vickers and the fine grain produced for
casting, there is no better. AND, even though alloys cannot be
welded together, as they have different melting points, ALL can
be soldered together with 1700 Pt solder. Then, a tungsten
burnisher can remove the seam. There are some new alloys on the
market that are heat treatable and can change the properties of
the metal simply by using a kiln or a torch. But until they are
common place, the best Pt alloy for casting in the international
arena is Pt/Co.

Hope that clears up some confusion. For more please
call me at (949) 760-8279

Jurgen J. Maerz
Manager of Technical Education
JA Certified Master Bench Jeweler

Jergen: Thanks very much for all your I never cease
to be amazed at the power of this list in connecting people and
advancing knoweledge. As you likely figured out, I’m a
practical jewelery mechanic and no metalergist. I simply
remember a time not so long ago, when plat/irridium was the
standard and I guess I tend to resist changes especially when
they seem to cause trouble for the less knowelegable like

Thanks again;
Steve Klepinger

Hi Jergen and Peter, I would like to know if there is any good
and technical literature about platinum and where can I find it.
I am following your conversations and I find them very
interesting. I have worked with platinum a few times but whitout
any real knowledge, (just enough to work it simply). I am
working almost only gold and teach jewelry all day long. But, as
we know, platinum working is not a basic technic to teach, but
may be it could be. Waiting for an answer Thanks

Vincent Guy Audette
Quebec City

Vincent, Jurgen’s “the man” here. His organization, PGI,
publishes a fair bit of excellent specifically about
platinum. There are some german texts that deal with it too.
Frie and Borel sells a couple practical goldsmithing softbounds,
and one of them is actually “practical platinumsmithing”. But I
found them very pretty photography and not as much actual
detailed didn’t read the german text though, only
the bits translated into english. Nice enough, still.

But as I said, PGI is your best source, so far as I can tell.


Because of the incredible rise of platinum consumption in the
US, Platinum Guild created a video called “The Platinum Expert”.
This video gives you a wealth of about working with
platinum. It is available by sending a check for $40.00 to
Platinum Guild International USA, "The Platinum Expert Video"620
Newport Center Drive, Suite 800 Newport Beach, CA 92660. Technical
papers and publications can be requested free of charge through
fax (949) 760-8780. Technical questions will be answered by me
if you call (949) 760-8882 and leave your name and number. Hope
that helps. Jurgen J. Maerz

Dear Terry and Steve; Well, I couldn’t just sit there and allow
this to go on. Here is my $.03;

#1 Cobalt/Platinum alloy is, in fact, Magnetic! This alloy is
used principally by casters or anyone selling cast products
(especially Stuller).

#2 The 10% iridium/ platinum (the old U.S. standard) is widely
used for manufactured milled or die-struck products such as
tiffany heads, low base heads or die-struck shanks.

#3 there are also platinum/ruthenium alloys used too.i.e.
Ruthenium/plat alloys.

#4 No platinum solder (not Hoover’s or especially not Stuller’s
"so called 1700 weld) will leave an invisible solder line. These
solders contain (according to Untracht) gold, palladium, and
some platinum. These solders are intended to be used to make
joints where any seam would be camouflaged by the design,i.e.,
the seam between a head and a shank, or when a wire is added
somewhere to make a prong, etc. Any joints, say on a shank, or
similar visible location MUST be welded. The seam will then be
composed of the same material as the parent metal.

#5 The irid/plat alloy can be welded without fluxes or boric
acid- it is basically non-reactive to the environment.

#6 the cobalt/platinum alloy does, however, seem to react (where
are you, Jurgen?). Any high-temp., long lasting flux (like Paste
flux)will help prevent the"crudding up" of the 950pt/50cobalt
alloy during this welding procedure.

#7 When one cannot be sure of which alloy is in use, one can use
PURE platinum for welding (readily obtainable from Hoover and
Strong) . This will leave a bright, clean fill. However, this
type of seam will be softer than one made from appropriate
parent metal alloy. It must be heavily burnished before
polishing and the seam must not be allowed to face the same
direction as the polishing buff or it will become “sunken” and
thus more visible during polishing. (not unlike working with
some 18K solders)

#8 Welding with anything other than the same alloy,will leave
some form of color difference. The mixing of any differently
alloyed components may also show differences in color. This can
be minimized with a good polish, or by (I hate this) a Rhodium
flash plating over the completed piece.

The technique of platinum fabrication is inherently different
from goldsmithing. In goldsmithing, we can rely on solders
being almost invisible and thus fabrication can be a little less
precise.Solders have some “fill” capability (even though it
should be scrupulously avoided).

Platinum fabrication must be more carefully planned so as to NOT
have any exposed seams and any seams must be precise, tight and
Welded with, hopefully, the SAME material. The solders do not
have ANY “fill” capabilities (for all intents and purposes).
These special problems associated with platinum fabrication make
it a more challenging, demanding discipline than gold
fabrication. Similarly, the demanding finishing process
associated with platinum also require a no “short-cut” approach.
Although Most capable jewelers used to working in gold can work
in Platinum, these subtle variations in metallurgical properties
require a -different- sensibility.----One requiring more careful
planning/designing, more thorough preparations and finishing.

If we keep these ideas in mind when we do platinum work, we will
find much less problems.

Best’o’Luck, Eben

Pt/Co 950 is indeed magnetic. It should be soldered with 1700
solder if you are sizing it. Roll your solder through a rolling
mill and make it very,very thin. Then wedge it in between the
seam and heat with a direct, oxidizing flame and solder. Use #6
eye protection. The alloy will slightly discolor during this
process. AFTER IT HAS COOLED DOWN, cover the ring with fire-coat
(Boric acid/Alcohol mix)and heat to about 900C or a bright
orange color. Then pickle it and the slight oxidation is gone. If
there is no recess area , it can also just be polished off. DO
NOT EVER USE flux when you heat Platinum to these high temps. The
borax or fluoride will enter the metal and contaminate it,
causing imbrittlement… This is the reason for NOT fire coating
it before the operation.

Pt/Ir is the standard in the US and is a very good metal, as
100% of it is PGM (Platinum Group Metal). It can be welded and
soldered at will and is very forgiving. Again DO NOT USE FLUX.
Fluxes are designed to work in the 1000 F range. (some more, some
less) the purpose is to keep the soldering are free and clear of
dirt, oxidation and such. PT/Co does’nt START to oxidize until
about 1200 CELSIUS. way out of the range of effective fluxes.

Pt/Ru is a wonderful alloy, designed for machining, die striking
and such. It is rarely cast and does not have very good casting
characteristics. Pt/Co is by far better. (see “the Platinum
Manufacturing Process Issues 3 and 4”)

Other alloys for casting in the US are Pt/Co/Cu. This Alloy has
the fluidity of Cobalt but without the magnetic properties. It
was developed by Engelhard-CLAL. Platinum alloys for export need
to contain 950 part per 1000 platinum, as that is the standard in
most countries. In US the standard is different.

An object made of PGM can be CALLED PLATINUM if at least 950
parts per 1000 are made of PLATINUM GROUP METALS, of which AT
LEAST 500 parts are platinum proper.

An object made of PGM can be STAMPED Platinum, if that ENTIRE
950 parts is platinum proper. It can also be stamped Pt950, Plat,
950 Pt or 950 Plat.

If an object contains between 850 and 900 parts per 1000
Platinum, the difference between that and 950 MUST be a PGM (
Iridium, Ruthenium, Osmium, Palladium, Rhodium), it can be
stamped respectably Pt850 or 850 Pt or 850 Plat. 900 Pt, 900 Plat
or Pt 900. The old marking IridPlat or 10% Iridium90% Platinum,
while still legal, are no longer being used.

Under 850/1000 Pt alloy MUST identify the alloy composition in
PGM to be legal, so , if you were to make a ring with 600 parts
per 1000 Platinum, the 350 parts that make the 950 mix must be
identified. You would stamp it Pt 600 Ir 350 or some such.

950 Alloys need not have anymore precious content to make up the
remaining 50. This is done , so that one can create a purpose
alloy, i.e. give it different properties. In Germany the work
horse alloy was 950 Pt/Cu. the copper gave it hardness and
ductility as well as malleability. It was an O.K. casting alloy.
Then in recent years the switch to Cobalt occurred, because
Cobalt is a grain refiner, makes the platinum wetter and thus
cast better.

Other common 950 alloys are Pt/Au, Pt/W, Pt/Pall etc. As
platinum is a dominant metal, the color does not change visibly
through these alloying techniques. Alloys are given different
properties. Some can now be heat treated, others are springy and
others machine well.

Working with platinum requires product knowledge. Know what the
alloys can and cannot do and dont use gold techniques when
working with them. Think of it like Diesel vs Gasoline. While
either will propell a vehicle, it is done in a different way.
Platinum is NOT difficult. It is Different.

Hope that helps.
Have a Platinum Day
Jurgen J. Maerz
Manager of Technical Education
JA Certified Master Bench Jeweler