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 Post subject: Green-red colour change stone
PostPosted: Fri May 21, 2021 3:45 pm 
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New to the forum,my first post, l hope that someone can shed some light on this stone.lt was bought as a loose stone, would like to make some jewelry and to find out what l have. The primary colour is green and it turns red in LED light, but only if background is grey black.lf the background is white the stone remains green. It glows strong red in black light, 5,5ct , clean in 25x magnification as l can see, baguette cut. I have no opportunity to perform even some basic tests (RI, spec. gravity test, termal conductivity test, l am not going to scratch glass with the stone). I know that I have enough information,but would like to know your opinions. I hope the photos are ok.


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 Post subject: Re: Green-red colour change stone
PostPosted: Sat May 22, 2021 3:05 am 
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baron wrote:
New to the forum,my first post, l hope that someone can shed some light on this stone.lt was bought as a loose stone, would like to make some jewelry and to find out what l have. The primary colour is green and it turns red in LED light, but only if background is grey black.lf the background is white the stone remains green. It glows strong red in black light, 5,5ct , clean in 25x magnification as l can see, baguette cut. I have no opportunity to perform even some basic tests (RI, spec. gravity test, termal conductivity test, l am not going to scratch glass with the stone). I know that I have enough information,but would like to know your opinions. I hope the photos are ok.


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 Post subject: Re: Green-red colour change stone
PostPosted: Sat May 22, 2021 5:36 am 
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Where are the photos ??

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 Post subject: Re: Green-red colour change stone
PostPosted: Sat May 22, 2021 7:00 am 
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danielle wrote:
Where are the photos ??

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 Post subject: Re: Green-red colour change stone
PostPosted: Sat May 22, 2021 7:30 am 
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danielle wrote:
Where are the photos ??


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 Post subject: Re: Green-red colour change stone
PostPosted: Sat May 22, 2021 1:43 pm 
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Can you explain why there is a cast of red across all the photos? White background photos have it as well. Without the basic gemological tests, it's just a mystery phenomena.

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 Post subject: Re: Green-red colour change stone
PostPosted: Sat May 22, 2021 3:24 pm 
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glhays wrote:
Can you explain why there is a cast of red across all the photos? White background photos have it as well. Without the basic gemological tests, it's just a mystery phenomena.

I was hoping that someone has something similar because the colour change is so distinctiv. I know l don't have enough information. I posted all information l have so far.


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 Post subject: Re: Green-red colour change stone
PostPosted: Sat May 22, 2021 3:54 pm 
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Looks like fluorescence.
My guess is it's something synthetic like CR yag, which can have an apparent color change from green to red because of its extreme fluorescence.

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 Post subject: Re: Green-red colour change stone
PostPosted: Sat May 22, 2021 4:28 pm 
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LOL, Stephen. The only stone I've ever seen with this kind of color weirdness was a YAG. I think you nailed it.


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 Post subject: Re: Green-red colour change stone
PostPosted: Sat May 22, 2021 5:54 pm 
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Barbra and Stephen, so the reddish cast onto the background is actually being cast out of the stone? Where I was thinking it was an outside light source being cast into the stone. #-o

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 Post subject: Re: Green-red colour change stone
PostPosted: Sat May 22, 2021 8:39 pm 
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Barbra Voltaire, FGG wrote:
LOL, Stephen. The only stone I've ever seen with this kind of color weirdness was a YAG. I think you nailed it.
Inside joke? What's laughable here?

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 Post subject: Re: Green-red colour change stone
PostPosted: Sat May 22, 2021 9:25 pm 
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It's a joke for me only, I'm afraid.
For the final practical exam at DGemG, everyone was given a box of 20 stones to ID.

The thing was, all the stones in the box were the same color and all were different gem minerals.
I got the green box.

Everything was straightforward until one, singly refractive stone, without displaying dichroism with a calcite dichroscope, appeared to faintly (but definitively) go red at the edges when viewed under different light sources. I'd never seen anything like it before.

RI was over the limit; SG around 4.5....after much speculation, I ID'd it as YAG fearing failure and humiliation. I was right.

I haven't seen the stuff since, but I'll never forget it.

That's why I really did laugh out loud when this series of pics was posted and Stephen slam dunked it as YAG.


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 Post subject: Re: Green-red colour change stone
PostPosted: Sat May 22, 2021 9:58 pm 
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I have a few big chunks of it from a laser crystal grower's scrap pile sitting on my desk :D

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