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A dark stain on a gold ring

Namaste everybody

A year and a half ago I made an Opal ring. [It is fabricated,] the
gold is 18k body and 22k bezel. [both Rose] A black stain become
apparent a few months after the ring was made, and shortly after a
lady had bought it. She wore it constantly. A month after the ring
was sold, I took it back and tried to fix the problem. I scrubbed the
dark layer out. Removed the little diamond and reset it. had a good
look with a 50x microscope, but couldn’t see any crack or pore!

My guess is that some dirt created a bubble in the original ingot,
that contained the black substance. under the rolling mill it has
become invisible, but still there must be an hidden cavity containing
a certain volume of the black stuff… as it has been cleaned out a
number of times, and still continue to ooze through its invisible
"spring". Hard scrubbing does temporarily remove the stain. [Because
of the opal I have not yet tried to clean it in the ultrasonic.]

I’ve uploaded a page with a large photo of the ring with the stain,
its on this page:

can anyone suggest an explanation to this uncomfortable stain? And
what can be done to repair this ring? The lady loves here ring. For
my self, I really can’t afford scraping this one ring and having to
make her a new one… which I will do if all repairs failed .

Thank you all very much

I would suggest that the gold alloy was not mixed properly. Did you
alloy the metal yourself or buy it form a supplier? Jerome

I would take a good look at her life style, work, etc. If this stain
was not present until after she bought the ring and wore it a while
she may be inadvertently exposing it to something that can cause the
stain. Has the stain always been in the same place and only the same
place? What was your source for the gold alloy? I would suspect a
reaction with the copper in the alloy rather than a contaminant cast
in by accident.

I am looking forward to see the answer to this problem as I like to
work with Rose Gold.


My experience tells me that either a filled pit, porous cavity or a
microscopic breakdown of a portion of the alloy as there was either
as contaminated wax of some flux got trapped during the pour. All
these can be affected later by exposure to bleach and other
household chemicals. Ringman John Henry

Hi bill and everyone Namaste

If I remember correctly this stain may have been there before the
lady had bought the ring. Only in such an indistinguishable intensity
that neither me nor the lady have noticed it! But looking back, I do
have the feeling that it has started before she bought the ring.

There are no suppliers of alloyed gold in this part of India [as far
as I know…] There’s this wonderful family on one of the jewellers
streets that I buy my gold from, they usually mix the alloy for me as
they have a large charcoal furnace and the experience of a family
line. They do my refining as well.

It is possible that at times, the refining process they do, may not
remove some? impurities [this has happened before, resulting with an
alloy which was nearly unworkable.]

What can I do now to remove this stain from the ring in such a way
that it will not re-appear ?

In the past I did thought it works like a miniature spring of oozing
black stuff… and it would eventually exhaust itself. Will the heat
of soldering temp. help ?

The Pickle ?
Neutralizing ?
The ultrasonic ?
Caustic soda ?
Other kind of chemical ?

Please help me with this one. Love & Light akash

I’ve seen instances where a “stain” is formed by using a worn
washout rack where the coating splits and the metal becomes exposed,
and said rack is stood in an ultrasonic bath for many minutes. The
stain forms at the point of contact. It takes repolishing that spot
to remove the stain. Steve Burns

Please bare with me for trying to press this question farther… A
black stain is repeatedly forming on the gold surface at Only One
particular place.

It is definitely oozing from within! All other gold parts are in
perfectly normal condition. Can this ‘mysterious black spring’ be in
some way Neutralized ?

Here is again the link for a photo of that strangely stained ring:

Thank you all
Love & Light

I would try to find a jeweler with a laser, it would work near the
opal, if it is porosity, even a casting grain that did not melt
properly in the casting. Using a laser would re-melt the metal in
the area, you could even build up a new layer of gold, and with
using a smoothing beam you could remove most all of the laser work
and have very minimal clean up. Let us know what you plan to do or
what is your final outcome Ringdoc

The best repair is to drill out the contamination and fill with a
like alloy… fusing is the best way but hard solder will work also.
I had a titanium stirring point break once and had ended up in a
silver casting… it made a horrible black spot and I resolved by
molding and recasting it. Ringman John Henry

A quick test might help. Have you dropped some nitric acid on the
spot to see if you get a reaction? If it foams green, it is
undisolved copper.

On a couple of occasions, I have not completely melted my alloy when
casting an object or ingot. This may not become obvious for weeks or
even months.

If it is undisolved alloy, disolve it out with nitric acid and weld
in new metal.


The best way to resolve your problem may be to drill a hole in the
ring at the point where the stain is, tap it, and screw in a piece of
gold wire made from the same alloy. The end of the wire can be chased
down until it becomes invisible and ‘welded’ into the existing
surface. I wouldn’t drill right through the ring as it is more
difficult to disguise the presence of a wire plug on a highly
polished surface than on a decorated one. At least with this method
you will have some certainty that you have completely and physically
removed any internal source of the dark stain.

Best Wishes,
Ian W. Wright
Sheffield UK

Hello All,

In reading a link recently provided to the article “Alloying in the
Small Shop” ( I found
the following which might shed some light on this earlier topic of
the “dark stain”:

“A particular example of bad housekeeping occurred early in my
career. For granulating I used a plastic coated drum with a container
on the bottom to catch the granules. I didn’t empty the drum each time
I granulated; in fact, sometimes I would not empty it for up to a
fortnight. Eventually I began to get complaints of black spots in the
castings. On close examination under the microscope, a small piece of
magnetic substance was extracted from a casting. This was identified
as iron. The plastic lining in the granulating drum had deteriorated
allowing the water to rust the drum. The iron oxide thus formed was
collected by the granulation and reconverted to iron during the
subsequent melt.”

Given the conditions under which Akash received his alloys it sounds
plausible that a similar problem to that quoted above may have

Trevor F