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 Post subject: yehuda and ammonia cleaners
PostPosted: Sat Oct 08, 2016 11:30 am 
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Just did the CGA exam for recertification.
One question was "Glass filled diamonds can be damaged by": correct answer a jeweler's torch. But... another possible answer is "ammonia-based jewelry cleaners" and that is counted as incorrect.
We sell yehuda fracture-filled diamonds and Yehuda tells us that ammonia based cleaners can harm the filler. They recommend a soft brush and soapy water...
We have carried them for years but were only informed about ammonia about a year ago. Also, rhodium plating solution might possibly damage the filler as will the pickle, of course.
Still learning.


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 Post subject: Re: yehuda and ammonia cleaners
PostPosted: Sat Oct 08, 2016 2:11 pm 
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I don't think the Yehuda treatment is glass. From Wikipedia: "This process, which involves the use of specially-formulated solutions with a refractive index approximating that of diamond, was pioneered by Zvi Yehuda of Ramat Gan, Israel."

Glass can be affected by high concentrations of alkali, but ammonia, a weak alkali, is commonly used for cleaning glass, either by itself or as a component of commercial cleaners.


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 Post subject: Re: yehuda and ammonia cleaners
PostPosted: Sat Oct 08, 2016 4:26 pm 
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Yehuda is a high RI glass. Yehuda responded that their filler is not stable to ammonia based jewelry cleaners when asked.


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 Post subject: Re: yehuda and ammonia cleaners
PostPosted: Sat Oct 08, 2016 4:51 pm 
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Sounds like the kind of question I always hated - the more you know, the more likely you are to get it wrong.


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 Post subject: Re: yehuda and ammonia cleaners
PostPosted: Sat Oct 08, 2016 4:54 pm 
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Specifically see Gems & Gemology fall 1994 Vol XXX, page 142. Refering to the Yehuda proceedure "...briefly stated this technique proceeds as follows: the diamonds are first cleaned then filled with molten glass at high temperature..."
Also see Gems & Gemology Summer 1989, page 79.
"...therefore this particular material is undoubtedly a lead-containing glass-like material".
The complete articles are interesting.
We carried Oved filled diamonds...basically the same filling technique, perhaps a slightly different formula.


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 Post subject: Re: yehuda and ammonia cleaners
PostPosted: Sat Oct 08, 2016 11:48 pm 
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You are correct mowgli2001! Yehuda uses a lead based glass filler which I have been told can be adversely affected by ammonia based cleaners.....of course a torch would be more immediately destructive....a real "oops" moment.


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 Post subject: Re: yehuda and ammonia cleaners
PostPosted: Sun Oct 09, 2016 9:06 am 
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I wonder what the glass composition is. I've never seen lead glass with an RI over 1.9. If the RI doesn't match, wouldn't it be visible?


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 Post subject: Re: yehuda and ammonia cleaners
PostPosted: Sun Oct 09, 2016 4:07 pm 
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But it is visible (at least in the samples I have seen). You easily guess something is wrong.


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 Post subject: Re: yehuda and ammonia cleaners
PostPosted: Mon Oct 10, 2016 1:13 pm 
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An Update on Fracture Filled Diamonds
[pdfview]http://lapidaryworld.com/pdf/f94_fracture_filling.pdf[/pdfview]


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