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Natural or Synthetic?
Both Natural 0%  0%  [ 0 ]
Both Synthetic 33%  33%  [ 1 ]
A Natural, B Synthetic 0%  0%  [ 0 ]
B Natural, A Synthetic 0%  0%  [ 0 ]
Buy from a reputable source 33%  33%  [ 1 ]
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 Post subject: Suspiciously Clean Emerald
PostPosted: Sat Dec 28, 2019 3:32 pm 
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After several years of searching for high quality emerald specimens where I am, I've come upon 2 in the same week. They are .52ct (slightly bluish green) and 1.00ct (very slightly yellowish green?). The cuts are lacking, but otherwise these are the finest emeralds I've personally examined.

What I hope to accomplish with this thread, is to determine if it's possible for an expert (which I'm not) to establish a reasonable degree of certainty as to whether these are natural or synthetic using standard gemological tools.

Ultimately these will go to GIA or AGL for verification, but I'm hoping I can get some participation here in helping me conduct a thorough analysis first. After all, if the only thing I ever learn how to do is send a stone to a lab, I'll never become much of a gemologist!

-Sean

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Last edited by Mr.H on Sat Dec 28, 2019 4:58 pm, edited 1 time in total.

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 Post subject: Re: Suspiciously Clean Emerald
PostPosted: Sat Dec 28, 2019 3:55 pm 
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If you have already confirmed the species identification as beryl, a microscope is one of more useful tools for assessing synthetics, though to be honest I am not entirely sure which inclusion features you'd look for in emerald.
Some synthetic emeralds contain copper, these I suspect would have an unusual spectrum. Not likely to be helpful but something to keep in mind.

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 Post subject: Re: Suspiciously Clean Emerald
PostPosted: Sat Dec 28, 2019 4:03 pm 
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Here are the results of my analysis...
Specimen A: 0.52ct slybG Emerald, Cushion Cut
Purchase location: Afghanistan
Purchase price: $2k/ct
SR/DR: Doubly Refractive
Optic Figure: Uniaxial
Dichroscope Reaction: Yellowish Green / Bluish Green
Pleochroism: Observed
UV LW/SW: Inert / Inert
RI: 1.562?
Birefringence: Unable to determine
Spectroscope: Unable to determine absorption pattern (poor equipment and/or lack of skill)
SG: Average: 2.8388 (1 - 2.7895, 2 - 2.8418, 3 - 2.8883, 4 - 2.7968, 5 - 2.8804)
Inclusion Analysis: Only 1 notable inclusion identified, a long, tube-like inclusion on one corner, running parallel to the table. Upon higher magnification, it's made of small crystalline structures resembling a healed fracture. I think this is a growth tube, but I am not certain. It could also be a healed fracture, or a "spicule" or "streamer" as seen in hydrothermal synthetics.

Conclusion: I'm unable to conclude if this is natural or synthetic. The RI seems to low, yet SG seems to high. It's a small stone so my system for measuring SG is probably not precise enough to distinguish between a flux/hydrothermal synthetic (2.65 - 2.69) and a natural stone (2.66 - 2.78 for the references I've found). The RI distinction between synthetic and natural is also very close (1.560 - 1.565 vs. 1.566 - 1.600) and my refractometer does not display to the 1000th. Likewise, the differences in birefringence are miniscule (0.003 - 0.004 vs. 0.004 - 0.010). I cannot make out birefringence in this stone, but if it's on the low side for natural, I doubt I can see 0.004 on this refractometer (perhaps I'm just too inexperienced). The lack of any signature emerald inclusions leaves me highly suspicious. My research indicates Gilson synthetics are the only notables that do not react to UV, so if not natural, my thought would be a Gilson.

Tube or spicule in bottom-left corner:
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Unusual surface flaws:
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 Post subject: Re: Suspiciously Clean Emerald
PostPosted: Sat Dec 28, 2019 4:06 pm 
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Refractometer, Specimen A:
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 Post subject: Re: Suspiciously Clean Emerald
PostPosted: Sat Dec 28, 2019 4:21 pm 
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Specimen B: 1.00ct slyyG Emerald, Oval Cut
Purchase location: Afghanistan
Purchase price: $2k/ct
SR/DR: Doubly Refractive
Optic Figure: Uniaxial
Dichroscope Reaction: Yellowish Green / Bluish Green
Pleochroism: Observed
UV LW/SW: Inert / Inert
RI: 1.57?
Birefringence: Unable to determine
Spectroscope: Unable to determine absorption pattern (poor equipment and/or lack of skill)
SG: Average: 2.7492 (1 - 2.7729, 2 - 2.7576, 3 - 2.7350, 4 - 2.7425, 5 - 2.7387)
Inclusion Analysis: Small fingerprint / partially healed fracture, growth tube-like inclusion, and what could perhaps be a 2-phase inclusion. Upon higher magnification, it’s very difficult to determine if they are growth tubes or “nail head spicules”. I think this is a growth tube, but I am not certain. I can also not quite tell if there is a 2-phase, partially healed fracture, or something like a platinum platelet with streamers coming off of it.

Conclusion: In my non-expert opinion, this is a natural emerald. I was unable to observe birefringence, but perhaps my equipment is not precise enough to measure. RI and SG seem to be within acceptable range. I tested a 1ct diamond for SG as a control, with a result of 3.5276, so I believe my SG test was reasonably accurate. I’m not experienced enough with inclusion analysis to know with certainty that the inclusions in this stone are natural, but that is my uneducated guess.

2-Phase Inclusion?
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 Post subject: Re: Suspiciously Clean Emerald
PostPosted: Sat Dec 28, 2019 4:27 pm 
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Specimen B: Growth tubes, or "comet tail" with small "nail head" spicules to the right?
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Specimen B - Refractometer:
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 Post subject: Re: Suspiciously Clean Emerald
PostPosted: Sat Dec 28, 2019 4:39 pm 
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Stephen Challener wrote:
If you have already confirmed the species identification as beryl, a microscope is one of more useful tools for assessing synthetics, though to be honest I am not entirely sure which inclusion features you'd look for in emerald.
Some synthetic emeralds contain copper, these I suspect would have an unusual spectrum. Not likely to be helpful but something to keep in mind.


Hi Stephen,
I really appreciate you making me feel welcome here. Regarding inclusions, what I'm looking for to ID synthetic is comet tails, nail head spicules, gas bubbles, and metallic looking inclusions that are translucent under all lighting conditions which could be platinum from a crucible. Of course, I'm not yet confident I would recognize it if I was looking at it, but that's what I'm keeping in mind when I look. Unfortunately I don't have immersion liquid...if I did I would also be trying to spot the wavy growth zoning I've read about in hydrothermal synthetics. I've been able to spot some textbook 3-phase inclusions in some of the emerald I've examined here, verifying it's natural origin. However identifying the treated areas of those stones was beyond my current skill level.

These samples are a real challenge for me, since they don't have much of anything. Some of the pictures I've posted are up to 120x and my glass isn't good enough to get crisp at that zoom. The inclusions in these stones are very small and very few.


Last edited by Mr.H on Sat Dec 28, 2019 6:02 pm, edited 1 time in total.

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 Post subject: Re: Suspiciously Clean Emerald
PostPosted: Sat Dec 28, 2019 5:26 pm 
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Perhaps I spoke too soon regarding my conclusion on Specimen B. Have a look at this...seed plate?

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 Post subject: Re: Suspiciously Clean Emerald
PostPosted: Sun Dec 29, 2019 5:11 pm 
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If I many suggest, start with this link, read through the articles and report back.
https://www.gia.edu/gg-general-search?q ... c+emerald+


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