AGTA TUCSON GEM AND MINERAL SHOW: FEBRUARY 4-9 2020
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 Post subject: Possible Imitation of a Demantoid?
PostPosted: Wed Dec 25, 2013 11:56 pm 
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I'm at the end of my 3 year formation in jewelery. I had a introductory class in gemology wich was very interesting and i am thinking of enrolling to AIGS. I got this usb microscope today and i decided to check out my gem collection and found this inclusion that i have seen somewhere but i cannot recall where. I think its in synthetics. I bought this stone when i started my jewelry class for cheap at a gem show as a demantoid garnet.

all in all i'm interested to know if i have a synthetic specimen or something else.


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 Post subject: Re: Possible Imitation of a Demantoid?
PostPosted: Thu Dec 26, 2013 4:00 am 
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Looks like a fingerprint inclusion.


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 Post subject: Re: Possible Imitation of a Demantoid?
PostPosted: Thu Dec 26, 2013 11:28 am 
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Have you tried testing it?
Polariscope reaction?
Refractive Index?

Demantoid garnet is the ONLY green gem which is attracted (actually picked up) by a rare earth magnet. Do you have one?

Demantoid garnets are not made synthetically.


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 Post subject: Re: Possible Imitation of a Demantoid?
PostPosted: Thu Dec 26, 2013 7:53 pm 
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i do not have the tools at my disposition, but i will definitely check it out when my school opens after the holidays.
thank you


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 Post subject: Re: Possible Imitation of a Demantoid?
PostPosted: Fri Dec 27, 2013 1:59 am 
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I would call that stone andradite, not demantoid.


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 Post subject: Re: Possible Imitation of a Demantoid?
PostPosted: Fri Dec 27, 2013 5:26 am 
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Bill Hanneman wrote:
I would call that stone andradite, not demantoid.

Dare I say... Topazolite? :lol:

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 Post subject: Re: Possible Imitation of a Demantoid?
PostPosted: Sun Dec 29, 2013 1:19 pm 
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andradite garnets:

imitations/confusions:
glass, other garnets (grossular for instance), yag, synthetic corundum, spinels, synthetic spinel, cubic zirconia, zircon (low), sphalerite, titanite, synthetic periclase, doublets...None of these would make a very good imitation, though (easy detection through classical gemology testing)

treatments:
fracture filling (colorless or coloured) and surface coatings (coloured) are possible in any gem (detection: microscope)
Low heating has been used to improve the color of demantoid (detection: not possible, not even in the lab)
And to my knowledge garnets arn't irradiated as it wouldn't improve the color.

synthetics: no existing synthetic to this day


Last edited by cascaillou on Mon Dec 30, 2013 12:28 am, edited 1 time in total.

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 Post subject: Re: Possible Imitation of a Demantoid?
PostPosted: Sun Dec 29, 2013 3:13 pm 
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Excellent info, cascaillou.

That is why I always suggest standard gemological testing with unknowns. One might be surprised to discover it is not even close to what they suspect it is. Speculation is futile when you haven't a clue what you're dealing with.


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 Post subject: Re: Possible Imitation of a Demantoid?
PostPosted: Mon Dec 30, 2013 12:06 am 
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agreed, with very repeated contact with gems you might develop some instinctive feeling about what is what and what it's not, but even then you might find yourself surprised that the stone in your hand is something you simply hadn't thought of...or possibly not even heard of. Which is precisely where testing comes into play.

Concerning the info I shared here: I simply love my books. Building up an accurate and exhaustive library is indeed vital. So is it to keep the data up to date (thank you gemologyonline!)


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 Post subject: Re: Possible Imitation of a Demantoid?
PostPosted: Sun Jan 19, 2014 5:56 am 
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Barbra Voltaire wrote:
Demantoid garnet is the ONLY green gem which is attracted (actually picked up) by a rare earth magnet.


Peridot ?


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 Post subject: Re: Possible Imitation of a Demantoid?
PostPosted: Sun Jan 19, 2014 1:36 pm 
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Peridot apparently can be dragged, but not picked up.


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 Post subject: Re: Possible Imitation of a Demantoid?
PostPosted: Mon Jul 07, 2014 5:34 pm 
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Barbra Voltaire wrote:
Peridot apparently can be dragged, but not picked up.


Yep, I confirmed that myself the day before yesterday :D (yeah, I know this is an old topic but I was really excited to learn about magnetic reactions in gems, I had to test EVERYTHING lol)


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 Post subject: Re: Possible Imitation of a Demantoid?
PostPosted: Mon Jul 07, 2014 11:39 pm 
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Barbra Voltaire wrote:
Demantoid garnet is the ONLY green gem which is attracted (actually picked up) by a rare earth magnet.

That sounds like a challenge to me :lol:

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 Post subject: Re: Possible Imitation of a Demantoid?
PostPosted: Tue Jul 08, 2014 12:02 am 
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The challenge is with Kirk Feral!
Although, I'm listening........... :wink:


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 Post subject: Re: Possible Imitation of a Demantoid?
PostPosted: Sun Jul 30, 2017 11:23 am 
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yes i tested the gem and it's an andradite garnet, not quite demantoid.


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