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Diamond turned brown


This past week, I did a cast-in-place sterling silver pendant with
three 2.5mm diamonds (color G, grade SI, matched, round brilliant). I
did NOT use debubblizer (see previous postings as to problems that
happened with that). Just did a straight casting - wax, stones,
investment. Burned out normally, cast into sterling silver, allowed
to air cool for a bit over an hour before digging it out of the
investment. Everything looked normal at that point, except one of the
diamonds was brown. I figured it was just still a bit warm, so
finished cleaning it up, put it in the ultra and then in the pickle.
2 hours later, the stone was STILL brown. It also looks like it has a
bit of a “metallic” glint to the surface - almost like an

The other two stones are fine.

Does anyone out there have a clue as to: 1. What happened? How to
prevent it happening in the future?

  1. How can I fix it? Is there anything I can soak it in, heat it
    with, etc., that might restore it to the original color?

Many thanks for any help!

And Happy Thanksgiving for all of your Orchidians in the U.S.!

Karen Goeller


Cubic zirconia turns brown when excessively heated. Did you test the
stones before casting them in place ? Ron Mills, Mills Gem Co.Los
Osos, Ca.


hello Karen,

according to my knowledge you must try two things:

a) dipping the piece in 10% sulfuric pickle (i dont know whether you
do it after ultra or not) or a much better option

b) cleaning the piece by steam cleaner.

i dont think there is any metal over diamond, it must be dust or any
other organic thing.

Hitesh Satikunver
Tanvi Arts
Mumbai (India)


Hi Karen,

Some diamonds are laser treated to take out some of the more obvious
inclusions. This leaves microscopic holes that are not noticeable
but that are susceptible to high heat particle intake and might
change the appearance of the stone. This is also how they color treat
diamonds (manufacturers are not obligated to inform the public when
they laser treat for carbon spots).

This might be the case of your diamond turning brown. There is no
remedy for this. It has only been in the past 8 to 10 years that
jewelers have cast stones in place. The manufacturers that treat
diamonds never suspected that they would be cast in place.

If this is the case with your diamond, the only thing to do in the
future is to look at the stones under a diamond microscope to detect
any laser holes before casting in place.

Dean Gordon

GOLDesigner Ltd.
Gold casting svcs.


Karen- i turned one orange once, sounds like it’s time to get your
check book out good luck -goo


A few years ago, I was retipping a stone that turned brown. I was
extremely puzzled, as this was someones stock and I should have been
informed if the stone had been treated. As happened, this stone had
been drilled and filled. A laser was used to drill the stone, the
darker inclusions were dissolved out with hydrofloric acid and the
resulting cavity was injected with transparent plastic. The treatment
looked great! Most of these stones exhibit a “purple flash” from the
pavilion side, but face up quite well. If this is what has happened
to your stone, it can be retreated.


Hi Karen,

dipping the piece in 10% sulfuric pickle solution

It’s worth to try what Mr. Satikunver says, and in addition I’ve
also heard that you not only dip it in, but boil the piece in the
pickle solution for some time. Every thing is worth to try, as long
as it doesn’t harm.

I hope it works, please let us know if you find a solution.

Best regards.


About 5 yrs ago, I had an unusual thing happen with a diamond that I
remounted. An antique jewelry dealer that I have been doing boxes
full of goods for years, brought in a ring she had purchased at an
auction. It had 2 large diamonds, a 1.31 carat diamond and a 1.60
carat diamond, set in a ladies mtg that was aprox 50 yrs old in
styling. Both stones showed no carbon visible under 10x loupe, and
were relatively clean all around. I mounted the 1.60 in a ring for
her husband, and the 1.31 in a ring for her. Everything looked fine,
she paid, picked up, but about2 weeks later came back with her
husbands ring and pointed out that there was a black spot visible
thru the table of the diamond. It was visible to the unaided eye. I
put it in the ultrasonic for a couple minutes and it was gone.
Everythings fine, right? Hardly! About 2 weeks later the spot is
back, so I louped it and found no laser drill hole leading down to
the spot, and again, put it in the ultrasonic cleaner. The spot was
gone and she went home again, only to have her return in a couple
more weeks. To this day, if I put it in the ultrasonic, the noticable
black carbon spot dissapears, and returns every couple weeks. I have
placed it in my GIA Gemscope and cranked the power way up, as far as
it will go, and still find no clue whatsoever about the cause of
this. Any guesses by anyone?

Ed in Kokomo

I have placed it in my GIA Gemscope and cranked the power way up,
as far as it will go, and still find no clue whatsoever about the
cause of this. Any guesses by anyone? 

I had a ring do exactly that once. Drove me nuts. The fix was that
eventually, in frustration, I unset the stone. The mounting was a
platinum cast bezel, and I noticed, in area rather under the actual
seat, a spot on the metal where not quite enough metal had been
cleared out under the stone, and the stone had been in actual contact
with the platinum. It was clearly this, since in the middle of this
area that was a mix of burred seat and prepolished smooth platinum,
was this clear sharp facetlike impression of a facet junction where
the diamond had pressed itself slightly into the metal. It had done
this well enough to create optical contact with the diamond, just
like a fluid spot wetting the diamond would have done, and whenever
temps and cleanliness were good enough for this to remain the case,
that spot contact looked totally dark. reflections of it visible
elsewhere in the stone appeared as though they were in the stone, not
on it’s pavilion surface. I’m wondering if something like this may
have occured in your case.