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?
Posted: Sun Dec 29, 2013 1:19 pm
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Joined: Sun Jun 28, 2009 9:56 am Posts: 1284
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.
Post subject: Re: Possible Imitation of a Demantoid?
Posted: Sun Dec 29, 2013 3:13 pm
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Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
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.
Post subject: Re: Possible Imitation of a Demantoid?
Posted: Mon Dec 30, 2013 12:06 am
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Joined: Sun Jun 28, 2009 9:56 am Posts: 1284
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!)
Peridot apparently can be dragged, but not picked up.
Yep, I confirmed that myself the day before yesterday (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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