McPherson Gem & Mineral Club Sale & Swap: Friday 3rd - Sunday 5th May 2019: McPherson, Kansas
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 Post subject: Re: Trying to determine garnet variety
PostPosted: Mon Jan 28, 2019 7:09 pm 
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It you want to send a small bit of the material to me, I'll test it and even mail it back to you.


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 Post subject: Re: Trying to determine garnet variety
PostPosted: Tue Jan 29, 2019 5:15 am 
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thanks Barbra!
Id love to. please PM the address and Ill get it sent out this week.
No need to send it back to me, I got these quite cheap so Im happy for you to keep it : )


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 Post subject: Re: Trying to determine garnet variety
PostPosted: Tue Jan 29, 2019 6:39 am 
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Please Barbra keep us updated about the results. I am a bit puzzled by the possibility of a color change colorless stone (?) and by a garnet glowing under SWUV.


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 Post subject: Re: Trying to determine garnet variety
PostPosted: Tue Jan 29, 2019 2:20 pm 
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Of, course. :smt112


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 Post subject: Re: Trying to determine garnet variety
PostPosted: Wed Feb 13, 2019 6:10 pm 
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Hi everyone.
I received the stone.
Weight: 0.51 carat
Shape: Faceted pear

It never appears colorless in any of my lighting conditions:
Color: Pale Purplish Pink in incandescent light:
Image
Pale Very Slightly bluish brown in daylight:
Image

UV: Very faint red LWUV, Inert SWUV
Magnetic response: drags

Gemmoraman identification: PYRALSPITE (pale pastel color-change pyrope in my opinion)
See Kirk Feral's Page for more detail
Image

The inclusion scene consists primarily of well formed crystals. No rutile was observed:
Some of these inclusions almost looked like phase inclusions within negative crystals, but feel free to add your own thoughts here.
Image

GIA article on pastel pyrope:


Hope this helps Raj_uk. :D


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 Post subject: Re: Determining garnet variety: pale pastel color-change pyr
PostPosted: Tue Feb 26, 2019 9:10 am 
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Apologies for the later response !

Thank you so much, you've been incredibly helpful and I cannot tell you how much I appreciate the time you've taken to carry out all this testing and provide me with the information article.

I notice the gem I sent was not colourless, but it was one of the larger ones in the parcel so I though it would be easier to test for you.

Im off to digest that article, thank you kindly once again :)


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 Post subject: Re: Determining garnet variety: pale pastel color-change pyr
PostPosted: Tue Feb 26, 2019 12:58 pm 
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My pleasure! Thanks for sending me the sample. :D


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 Post subject: End-Member Grossular Garnet with Color-Change Effect
PostPosted: Tue Apr 09, 2019 1:25 pm 
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We have discussed odd color change garnets on this thread before.
Here is an article to add to our collection
Quote:
Abstract
Most color-change garnets in gem market are intermediate in composition or solid-solution between pyrope and spessartine end-members with a trace of vanadium or vanadium-plus-chromium responsible for their color-change phenomenon.
Some chromium-rich pyrope and grossular-andradite solid-solution with color-change effect have also been reported previously. In this study, two new color-change grossular garnets were examinedat the GIT-GTL.

Their UV-Vis spectra and chemicalcompositions revealed that the stones were a rare almost-pure end-member grossularite with chromium-plus/minus-iron as the significant color causing elements.

https://www.git.or.th/eng/testing_cente ... 201801.pdf


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