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 Post subject: GO Joint Research Project I...
PostPosted: Wed Nov 16, 2005 4:38 pm 
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....Do certain synthetic emeralds reacting to simple penlighting with standard LED or incandescent bulbs transmit or fluoresce a visible red hue?

...if so, what general classifications as to type synthesis and/or brand can be made?

...can the effect be observed in any natural emeralds, as well, using the same sources?

...does the process have a practical application for separation or ID'ing synthetic emeralds.

GENESIS of project:
Pics of the effect is show below.

ImageImage

After observing the effect in two of three synthetic emeralds that I have on hand, I pulled out about 15 natural, mostly Columbian Emeralds, all of which failed to yeild the reaction.

Tools required to participate:
1. PENLIGHT ONLY

Study stones:
1. Whatever synthetic or natural emeralds that you have on hand.

Investigation procedure:
1. Turn on penlight
2. place table of stone face down on penlight.
3. observe
4. employ several different placements and angles and observe.
5. record and POST your findings HERE. preserve your records, along with specifics of stones as to brand, method of synthesis, origin, color info, SG's, RI's, etecetc - anything that you have on hand.
----initially only more general info need be posted ...pics welcome but not necessary.

SUGGESTIONS?

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PostPosted: Wed Nov 16, 2005 5:34 pm 
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The stone depicted in the above post.

1. Emerald, syn.
2. probably flux, manufacturer unknown
3. VVS medium dark bG
4. SG ~2.70
5. Spectrum: very pronounced typical in red, distinct absorption ~620 and transmission band at ~610 , possible lines in blue and bv.
6. light source: LED
7. reaction: see pics in above post

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 Post subject: Uh oh...
PostPosted: Wed Nov 16, 2005 11:36 pm 
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I feel like I'm crashing the party here, but it should be noted that this reaction is already known in certain synthetic emeralds, chiefly the hydrothermally-grown Linde emeralds. This probably also applies to Regency emeralds, which were grown under identical conditions. Linde synthetic emeralds' most distinctive feature is their extremely strong red fluorescence, even under (high-intensity) white light -- hence your observation. AFAIK, this hasn't been noted in any other brand.

Linde (or Regency) synthetic emeralds are also characterised by so-called "nail-head" inclusions (i.e., a growth tube capped by a phenakite crystal); a lack of feathers; fine colour; and physio-optical constants very close to natural emerald. These synthetics were produced from 1965 until about 1970, and are still encountered today. It's possible your stone isn't a Linde, but in all probability it is. For more detail on characteristic differences between the various synthetic emeralds, see:
  • Anderson, B. W., and Jobbins, E. A. (Ed.) (1990). Gem Testing, 10th edition; pp. 238-248. ISBN 0408023201 (Includes an excellent chart.)
  • O'Donoghue, M. (1997). Synthetic, Imitation & Treated Gemstones, pp. 97-108. ISBN 0750631732

That said, those are excellent pictures of the phenomenon. You've certainly got the scientific method down pat, and I look forward to more of your dabblings.

You may now commense the tomato bombardment. :)


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PostPosted: Wed Nov 16, 2005 11:57 pm 
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No party crash at all! AND what a time saver! LOL. Thanks for the comments and for the answer....

I really enjoy all of your responses. VERY authoritative - I never check 'em!

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 Post subject: You're welcome!
PostPosted: Thu Nov 17, 2005 12:19 am 
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You're eminently welcome! And, hey, if you can determine that those two stones are indeed flux-grown, it could be a new finding (or at the very least, it would be to me). I'd double-check for the reaction on my own flux emerald, but I seem to have misplaced it. :oops:


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PostPosted: Thu Nov 17, 2005 5:59 am 
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Ux4,

Good idea!

I will check all my emeralds with your methodology
I will give you the result here.

Right now, I can show you the emission spectrum of natural colombian emerald vs flux chatham synthetic emerald.
I use a blue filter (hydrated copper sulfat xtal) to absorb the red-orange region of the "exitatrice" light.
Image
I put the stone on the blue filter and I check emission spectrum in the red part.
As you will see the red emission zone it's much stronger in the flux synth emerald.

Colombian emerald:
Image
Chatham flux synth emerald:
Image

You can check this difference of red (aditive) with the Chelsea filter.
The same with LWUV exposition.

Nevertheless, I think that all these test (Chelsea, LWUV, spectrum, .. .probably penlight ;-)) are not diagnostic because I have seen a colombian emerald (from Chivor) that exhibited a strong red fluorescence!

However, a simple test like penlight is very interesting... I will check the battery of my maglite ;-)

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Jean-Marie Arlabosse
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PostPosted: Fri Nov 18, 2005 2:08 pm 
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gemca...

...excellent spectra!

...RE: the Chivor Emerald. With the SzS hand held spectroscope, I can get fluorescent response in the very included Colombiam stones, BUT no response with the penlight test. However, the VS and better Colombian stones don't give me much at all with the handheld. I will soon plot spectrographs which MAY reveal more information.

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PostPosted: Sun Nov 20, 2005 9:08 am 
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:( May be I do something wrong :roll:
Well! I give you my observations...

With a penlight (maglite): No red coloration for all my emeralds :?

Gilson Flux Synth emerald => the stone stay green when directly lighted by a penlight.
When I put this stone directly on a "optic fiber light" I see a red coloration on the fibers (at the contact zone with the synth emerald).

For the Chatham Flux, Russian hydrothermal synthetic emeralds.. and for naturals => nothing, the stones stay green all the time with the penlight or with an optic fiber light.

Note:
Gilson flux with LWUV exposure=> pinkish red reaction
Other => No recation (No strong reaction)

It seems to me that the stones that will show red coloration in penlight are the stones that show the strongest LWUV reaction...no?

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PostPosted: Sun Nov 20, 2005 9:58 am 
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Maybe you need the "sticky hole" thing to reproduce Ux4's experiment? :lol:


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PostPosted: Sun Nov 20, 2005 10:27 am 
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Gemca...

...More than likely, your findings are correct and inline with the information in the post above from Gregory. Gregory noted that the phenomona had previously been observed only in Linde Emeralds.
...the LW and SWUV reaction is strong with my sample Emeralds.

...'nuck, the sticky hole isn't necessary to get the reaction in the Emeralds that I observed.

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PostPosted: Sun Nov 20, 2005 11:13 am 
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Just teasing ya :wink:


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PostPosted: Sun Nov 20, 2005 11:32 am 
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AS IF!!!!!

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PostPosted: Sun Nov 20, 2005 1:33 pm 
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Image

My three synthetic emeralds. The oval and emerald cuts fluoresce. The pear does not. The two that do are notably bluer than the pear cut. The also tend more to dark than med-dark.

The two fluorescing stones are too blue, imho, while the pear is a finer(?) color.

The stones are IF, yeilding NO inclusions or method ID'ing features yet. So, I am thinking hydrothermal, which, if true, is consistent with Linde's.

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PostPosted: Mon Nov 21, 2005 5:25 pm 
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Somehow I think it was right on the ban thingy on a certain person we shall not name but posted the previous post!

I mean it's all in good fun, but the only funny guy around here is me. The rest needs to pay royalties.


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PostPosted: Mon Nov 21, 2005 7:52 pm 
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Name the evil provocateur, Doos!

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