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Will A "neodymium Magnet" Detect Hpht Synthetic Diamond?


ronk15a
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Dear Community,

 

I’m interested in finding out if a high powered Neodymium Magnet will allow you to detect an HPHT synthetic diamond? My understanding is that during the HPHT process a metal catalyst is used such as iron/nickel/cobalt...Will a “Neodymium Magnet†such as an N52 magnetize to an HPHT synthetic?

 

If yes; will the magnet magnetize to an HPHT annealed natural diamond? If anybody has an suggestions on other ways to detect HPHT please let me know? Thanks again!

 

Regards Ron

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Hi Ron,

 

No. The metal content is typically so low that you can't detect it with even a serious magnet and the ones that have that much in them are easy to spot with a loupe.

 

The way to spot HPHT synthetics is with a Raman spectroscope. You can get some clues using x-ray fluorescence and there are tools on the market for a few thousand dollars like the DeBeers DiamondSure that can separate out which ones you need to send to the lab for further investigation (assuming you don't have a Raman yourself). There's been a recent scandal at IGI over CVD synthetics and there's increased interest in this topic that may lead to some cheaper tools but they still don't provide a decisive answer.

 

As a consumer or a jeweler, it's even easier. You do it with the girdle inscription and the lab report.

Edited by denverappraiser
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Correct. Natural diamonds don't have metalic inclusions. HPHT treatment doesn't change the chemical makeup. If it's got metal in it, it's synthetic. The problem is that recently made HPHT synthetics have damn little metal in them and those that do you're unlikely to spot with a magnet or a standard sort of microscope.

Edited by denverappraiser
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Dear Community,

 

Is it possible to see reactions via a shortwave/longwave U.V. lamp? Specifically the one that GIA sells the (Multispec)?

My understanding is that under U.V. light the HPHT synthetic stones fluoresce green-yellow. Is this true?

What about HPHT natural; what color do they fluoresce? Does it vary; both in color/ and intensity.

I believe that the CVD synthetic stones fluoresce a reddish-orange (and now green-yellow). Is this true?

Is it accurate to say that diamonds that fluoresce blue under U.V. light are natural; because synthetic stones never fluoresce blue.

Regards Ron

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Pretty much "no" to all of your latest questions (other than HPHT-treated natural: yes, they do fluoresce, and it varies in colour and intensity).

 

A GIA report will cost a hundred dollars or so, and will establish without any doubt whether the stone is treated, synthetic or natural using appropriate instruments and carrying a fair amount of clout in the trade. A lot cheaper than trying to find shortcuts - which by and large are unreliable too.

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Dear David,

I recently received a response from Mr. Neil Beaty regarding magnetism and HPHT. If you wouldn’t mind, I would like your expert opinion on this specific matter. Thanks again!

GIA's Tom Moses, the senior vice president of GIA Laboratory and Research, and Wuyi Wang, the director of research and development for GIA New York, were featured speakers. Below is a link to an article dated 6/19/12. In the second to last paragraph it talks about HPHT synthetic diamonds and a dealers ability to identify them.

 

 

http://www.diamonds.net/News/NewsItem.aspx?ArticleID=40409&ArticleTitle=GIA+Explains+Synthetic+Identification+Processes+at+DMIA+Meeting

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Ron - the problem is as follows: yes, it's true that magnetic materials (iron group metals) are used as catalysts in production of HPHT synthetics, but the quantities of magnetic material normally present in the diamond are minute, detectable only under a microscope or through spectroscopic analysis. If you are "lucky" (?) enough to have an HPHT synthetic that contains enough metal to be attracted to a magnet in a macroscopic way, you won't need the magnet to identify the metallic slag - you probably won't need a loupe either nor will you want to buy a diamond heavily speckled with dark grey inclusions. My impression when reading the article is that Mr Moses meant the remark as a humorous one, but the article writer missed the humour.

 

Fluorescence is fine as a first test, but it is not sufficient: it can only rule out some natural diamonds (those without fluorescence, for example). To identify with certainty a synthetic (or HPHT treated) diamond, you need lab grade equipment and expertise - not least because even the fluorescence can be very localised and faint, not at all easy to spot without appropriate tools (e.g. darkfield illumination microscope with UV of the correct wavelength).

 

Again, if you have doubts on a particular stone that you are considering, you are much better off (financially as well as certainty-wise) submitting it to a reliable lab, or insisting that the seller does, than trying to identify it with Heath Robinson (or McGyver, whichever you prefer) methods.

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  • 1 year later...

A detailed research study to answer questions about magnetism in diamonds such as those posed in this forum was conducted by myself. Results were published in the Winter 2012 edition of Gems and Gemology. My research confirms what Tom Moses said at the DMIA meeting.

 

I found that 58% of HPHT synthetic diamonds contain iron flux particles in sizes and concentrations high enough that they could be detected with a neodymium magnet. CVD synthetic diamonds are not detectable in this way. Natural gem-quality diamonds are generally not attracted to a neodymium magnet, but rare examples do exist, and the first documented case is reported in my article.

 

To read the article, just google Detecting HPHT Synthetic Diamond Using a Handheld Magnet and download the pdf file from GIA.

Kirk Feral

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