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 Post subject: Color-change gem
PostPosted: Sat Dec 10, 2016 5:40 pm 
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Hello everyone,

I just want to share the pleasure that I have presently to try to identify by simple measures a gem.

About 2 years ago, I received an old ring from a dear aunt of mine who had passed away. From the model, the ring is at least 30 years old, probably more as 40-45 years old. I have never seen my aunt wear it. So it was not a ring that she was wearing for day to day activities.

As I was not well, I did not really take a good look at it when I received it. I only thought that the huge gem on it was glass and that it did not worth very much. But I kept it as it has belonged to my aunt.

Last week, I looked at it and discovered that it changes color. In the daylight, it is 2 colors: a bluish color with light purple. In the incandescent light, it is deep purple like amethist. I prefer the color in the incandescent light. The gem is faceted without window. So even on the top, it is all faceted. The gem is so clean of inclusions that I can litterally see throught it. If I look really close to it by a window, I can see replicate several times throught it the plant in the snow that is outside. I can see with the 10x loupe 2 littles chips. In the daylight, the blue seems more turquoise when I look at it really close.

Last summer, our youngest son rearrange the basement, so I have no acces to my microscope, refractometer and polariscope for the moment. So I can only make visual optic examination on it, unless I go see my brother who is gemmologist. As it is Christmas time, I am sure he has no time for that.

I do not think that this gem worth a lot of money. My aunt did not have a lot of money. But I am very intrigued by this drastic color change. I try to figure out what are the possibilities for this gem, just for fun, with my actual limited tools.

I did the tongue test. The gem is cold. And it has dichroisme in it during day time. So I hypothese that it is not glass.

I see that sapphire can be color-changing. But in that case, it would have cost a fortune to my aunt. So, I hypothese that it is not sapphire.

I read that garnet can be color-changing. I found picture on internet of color-changing garnet that looks like my gem. But they are not as huge. At that size, it would cost much more money that my aunt would have invest for it. And it seems that garnet do not reflect dichroim in the daylight.

Last night, with an incandescent hand lamp, putting the stone really near my face, I looked at the gem with the 10x loupe. The specter that I saw did not look as bi-refringent, but it was really elongated. I was able to see a lot a them without moving the stone, half the stone.

So with so little information, does someone want to play and give an other hypothesis?

Best regards.

Brigitte


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 Post subject: Re: Color-change gem
PostPosted: Sat Dec 10, 2016 6:11 pm 
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The answer is always V-doped synthetic sapphire. Very popular in inexpensive jewelry particularly in that era with a distinctive blue-purple/pink color change.

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Rough and cut classic and exotic synthetic gems:https://store.turtleshoard.com


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 Post subject: Re: Color-change gem
PostPosted: Sun Dec 11, 2016 12:38 am 
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And....usually misrepresented as alexandrite.


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 Post subject: Re: Color-change gem
PostPosted: Sun Dec 11, 2016 12:49 pm 
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Hello,

Thank you mister Challener and madame Voltaire.

I am happily surprised that you were able to identify the stone so precisely. Before your answer, I thought that synthetic sapphire was more expensive. I knew that it cost much less than natural sapphire but I did not think that it was so cheap.

By V-doped, do you mean vanadium?

Now the mystery is solved. I will maybe be able to later study it with my instruments to learn to identify some inclusions related to synthetic sapphire.

Thank you.

Brigitte


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 Post subject: Re: Color-change gem
PostPosted: Fri Dec 16, 2016 1:05 am 
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Yes, Brigitte, V=Vanadium.

-Tom


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 Post subject: Re: Color-change gem
PostPosted: Fri Dec 16, 2016 10:44 am 
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Thank you.

Best regards

Brigitte


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 Post subject: Re: Color-change gem
PostPosted: Wed Dec 21, 2016 6:00 pm 
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I love it!
I read this thread and saw Brigitte post this little quote..
"I am happily surprised that you were able to identify the stone so precisely."

Stephen and Miss B nailing it ....like a champ!!! =D>
Well done guys!!!

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 Post subject: Color-changing Amethyst question
PostPosted: Sat Feb 25, 2017 1:32 am 
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Hi everyone. I'm new.......
I have a stone that I need help with. Background: my father brought some stones home to my home around 40 years ago. I used to play with them when I was a little girl. Fast forward: I wanted to have a stone reset into a 14k basket setting, and took the stones to the jeweler to see if any would fit. The stone has ALWAYS been purple at her house, and labeled amethyst. When the jeweler put it under his light, it was blue!! He said this a blue topaz. I said No No No, its always been purple! I look on google and see that there are some color changing stones but not to this degree.
Pics are posted below: top pic is regular lighting, bottom pic is under our fluorescent light. We have both in my kitchen. I am so confused, and love some input. Thanks so much


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 Post subject: Re: Color-change gem
PostPosted: Sat Feb 25, 2017 3:22 pm 
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I have a similar stone that I am stumped over. I tried to start a new thread but it hasn't been approved yet. Can I post the pics on this thread possibly? I would appreciate any help. I am clueless about amethysts.
Image


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 Post subject: Re: Color-changing Amethyst question
PostPosted: Sat Feb 25, 2017 10:09 pm 
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Gee, you gotta love those helpful jewelers.....not.

There are a few things it could be. Neither of which is blue topaz or amethyst. Please take your unknown to a gemologist and have them test the stone with a refractometer, polariscope and microscope.

Let us know what you find out.


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 Post subject: Re: Color-change gem
PostPosted: Sat Feb 25, 2017 10:19 pm 
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These pictures aren't screaming vanadium doped sapphire to me. Anyone?
It is almost reminiscent of color changing glass:
Photos courtesy of YoMamaFindings
Image
Image

or color change fluorite:
Image courtesy of GemSelect
Image


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 Post subject: Re: Color-change gem
PostPosted: Sat Feb 25, 2017 10:47 pm 
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https://www.google.com/url?sa=t&rct=j&q ... AQ&cad=rja

has a vanadium garnet with a similar color change, but it was only 17 years ago, not 40.


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 Post subject: Re: Color-changing Amethyst question
PostPosted: Sat Feb 25, 2017 10:56 pm 
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That's what I was trying to avoid. My mom isn't interested in paying $200 to figure it out if it's worth $10. It's a curious thing since we had always seen it as a purple stone. More like when you have a missing piece at the end of the puzzle. It's annoyingly intriguing. Thank you for the advice though. It's much appreciated.


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 Post subject: Re: Color-change gem
PostPosted: Sat Feb 25, 2017 11:01 pm 
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Vanadium doped sapphire?? Hmmm.... of course not being in the business I have no idea about this. They did that 40 years ago? So am I correct to assume it's a synthetic stone? My jeweler had never heard of such a thing, but of course he is not a gemologist like you guys. I think I found the right place to post it.


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 Post subject: Re: Color-changing Amethyst question
PostPosted: Sat Feb 25, 2017 11:02 pm 
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Or...........you could get the help of your closest Gem & Mineral Club! They always have gemologists as members and they will usually help you out if possible.
http://www.rockhounds.com/rockshop/clublist.shtml

If you live in the Bay Area, you are welcome to bring them to my lab and I'd help you sort it out. Pro Bono.


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