Rivista Italiana di Gemmologia #2: Available NOW in English - September 2017; See Gemological Articles below for full details!
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 Post subject: Blue Amber
PostPosted: Wed Aug 13, 2014 10:18 pm 
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GIA wrote:
Color Phenomena of Blue Amber
Abstract
The greenish blue color observed in some amber from the Dominican Republic and Indonesia is actually fluorescence stimulated by ultraviolet (UV) light. A previous study described the color as iridescence over a yellow background, but it is in fact a surface fluorescence. Since this amber can be considered a long-wavelength pass filter with a half-pass wavelength at about 530 nm in its spectral transmittance, it does not transmit either UV or short-wave visible light. As this material completely absorbs light in the UV range and strongly absorbs light in the short-wave visible range, the stimulated blue color is confined exclusively to the surface. The amber from this study also showed the Usambara effect, the phenomenon in which color varies with the path length of light through a sample.


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 Post subject: Re: Blue Amber
PostPosted: Fri Aug 18, 2017 7:41 pm 
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Barbra do you have any pictures of this phenomenon? I've never heard of it and it sounds amazing! :shock:


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 Post subject: Re: Blue Amber
PostPosted: Fri Aug 18, 2017 11:28 pm 
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Click on the link, there are some pictures in the article.

LINK


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 Post subject: Re: Blue Amber
PostPosted: Sat Aug 19, 2017 10:09 am 
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Thanks to Barbra for the very interesting article I just read.

I like this kind of Amber.


Photos of Sumatra Blue Amber which I bought 3 years ago on a mineral fair:

Attachment:
Blauer Bernstein aus Sumatra Foto Tageslichtaufnahme und Foto unter UV Licht.jpg
Blauer Bernstein aus Sumatra Foto Tageslichtaufnahme und Foto unter UV Licht.jpg [ 85.65 KiB | Viewed 246 times ]

Attachment:
Blauer Bernstein-001.jpg
Blauer Bernstein-001.jpg [ 78.88 KiB | Viewed 246 times ]

Attachment:
Blauer Bernstein-002.jpg
Blauer Bernstein-002.jpg [ 82.29 KiB | Viewed 246 times ]


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 Post subject: Re: Blue Amber
PostPosted: Sat Aug 19, 2017 12:39 pm 
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I have to admit, this amber is pretty awesome.


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 Post subject: Re: Blue Amber
PostPosted: Mon Aug 21, 2017 11:05 am 
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That it exhibits phosphorescence is pretty amazing. :smt048


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 Post subject: Re: Blue Amber
PostPosted: Tue Aug 29, 2017 1:38 pm 
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Actually fluorescence in amber isn't unusual. It's quite intense in those samples, though.


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 Post subject: Re: Blue Amber
PostPosted: Tue Aug 29, 2017 3:28 pm 
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Agreed, fluorescence is more the rule than exception for amber, (esp. being a resin), Phosphorescence on the other hand is highly unusual, yes?


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 Post subject: Re: Blue Amber
PostPosted: Tue Aug 29, 2017 4:50 pm 
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my bad, I had misread fluorescence for phosphorescence. I don't know how rare the later phenomena is, though.


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 Post subject: Re: Blue Amber
PostPosted: Tue Aug 29, 2017 10:51 pm 
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As a general rule I have found phosphorescence is much less rare when you use one of those uv lasers (but I am too scared to use mine much).


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 Post subject: Re: Blue Amber
PostPosted: Wed Aug 30, 2017 10:32 am 
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Stephen Challener wrote:
As a general rule I have found phosphorescence is much less rare when you use one of those uv lasers (but I am too scared to use mine much).

Hmmm..We're still talking about amber right? I just had a go with ambers and copals from 6 different countries. Using the following: SW (4w tube), LW (375nm LED), and "UV" laser pointer (actual is 405 nm violet). None of these resins showed any phosphorescence.

This was more my own curiosity, and I think that the Sumatran material may be unique. I will see if I have any Australian amber.. perhaps that one might be phosphorescent?


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 Post subject: Re: Blue Amber
PostPosted: Wed Aug 30, 2017 11:13 am 
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UPDATE

I found both Aussie and Indonesian ambers in our stone specimen collection. The Australian did not phosphoresce but I was happy to see that the Indonesian did. I received the Australian from Maggie C. Pederson, and the Indonesian from dealer Anil Dholakia.


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 Post subject: Re: Blue Amber
PostPosted: Wed Aug 30, 2017 6:48 pm 
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Bear Williams- SGL wrote:
Stephen Challener wrote:
As a general rule I have found phosphorescence is much less rare when you use one of those uv lasers (but I am too scared to use mine much).

Hmmm..We're still talking about amber right?

No, sorry, I meant in general on minerals. I haven't done much testing on amber.


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 Post subject: Re: Blue Amber
PostPosted: Thu Aug 31, 2017 4:02 pm 
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Definitely so Stephen. Those 405nm laser pointers are fabulous for making stones fluoresce where you wouldn't expect them to. Seems they can cut through a certain layer of the Fe and make some electrons jump up. I have a half dozen of these lasers and we use them in the lab for multiple reasons.


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 Post subject: Re: Blue Amber
PostPosted: Thu Aug 31, 2017 5:05 pm 
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Barbara
I always enjoy the discussions you start. Educational and interesting.

It also helps pass the time when I am on hold with the insurance companies.... over 3 hours today so far and counting.


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