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PostPosted: Mon May 21, 2007 5:43 pm 
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Breeze,

A tip I picked up from Alan Hodgkinson is if you don't have a sodium light source or a correct yellow colour filter for your refractometer, you can use the transparent yellow cellophane wrapper from a Quality Street toffee, it works very well, although I am guessing you are probably American in which case you may not have Quality Street sweets, but maybe you could experiment with another type of confectionary wrapper!

Hope this helps,

Kerry.


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PostPosted: Mon May 21, 2007 7:11 pm 
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Location: The frozen north prairie :-/
In America it would probably be a butterscotch candy wrapper. Or, you can put regular table salt into a candle and it will produce sodium light. Of course, make sure your area is clear enough for a burning candle!!

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PostPosted: Mon May 21, 2007 7:28 pm 
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Lucky we have them in South Africa!
lol
I better start eating more chocolates... Just for the wrappers, of course.


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PostPosted: Mon May 21, 2007 7:52 pm 
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LOL I just happen to have butterscotch candies!!! I read in one of my books where the wrapper can be used!!!! But from what I can tell, looks like the light for my refractometer is going to work ok.

But thanks for the help guys! I learned so much yesterday, I have had to take a day off today, my head feels full!! hehehe

All I did today is just sit and look at all my gems...take them out, hold them, look at them so more, ..... I can't help myself :oops:


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PostPosted: Mon May 21, 2007 7:54 pm 
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Great... just what we all need... another excuse to eat more candies. ;)


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PostPosted: Mon May 21, 2007 10:31 pm 
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Hmmm Breeze's last comments remind me of a story a friend told me. A professor of his asked in class if there was anything wrong with a person who liked to collect doorknobs. No, the class answered. He says, "suppose this collector of doorknobs looks at them every day? Is there anything strange about that?" No, the class answered. Lastly, he said "What if he looks at them every day and *fondles* them before going to bed at night?"

Did I make my point?


*runs off to fondle his new stones*


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PostPosted: Tue May 22, 2007 9:57 am 
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You can get a facsimile of sodium light by going to your local camera store and ordering a Wratten 23A orange (they call it red) filter. There is also a company called Roscolux that makes plastic filters for stage and similar uses and they have a similar color in their R22 or R23 filters;
http://www.rosco.com/us/filters/roscolux.asp
Those are sold, along with polarizers and quarter wave plastic by McCrone's in Chicago and also by Edmund Scientific. None are expensive.

Wratten filters were one of the Kodak products that were an industry standard. A few years ago they sold the business to the Tiffen filter company.

HTH
Gene
Slinking off to fondle his gem instruments


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PostPosted: Tue May 22, 2007 1:45 pm 
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Just for the heck of it, I thought I'd try to photograph the spectra from a candle/salt light source.

Two images, the first more directly at the flame and the second directed a bit away from the flame.

Image

Image

Although the yellow can't be seen in the images, in person the sodium line appeared in the yellow/orange area of the spectrum.
I used another regular candle as a control. No emission line could be seen until I added salt.


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PostPosted: Tue May 22, 2007 3:31 pm 
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Very nice JB! I think the dd line would be even more isolated with a bunsen burner flame or propane torch.

My friend Ioannis Galidakis has posted some new stuff on lighting and color spectra on his award winning website.

http://ioannis.virtualcomposer2000.com/ ... ments.html

Gene


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PostPosted: Tue May 22, 2007 4:46 pm 
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Hi Gene,
I was afraid to try anything stronger than a candle flame without checking my Homeowners Ins. :lol: Nice weblink btw.

I had never used the candle/salt method before, so, I decided to do my own experiment using white light (mag lite), candle/salt light, then the monochromatic light that came with my refractometer.

My results are in and this is what I found. The mag lite produced a nice bright viewing scale but also a small full spectrum cut off line, maybe helped by my squinting and imagination to see the entire spectrum.

The candle/salt method narrowed the cut off to a more narrow blue/green appearing cut off. The light from the candle (Round tea lite candle and salt) although about the right height for the refractometer, just didn't produce a bright enough light for my liking.

The monochromatic light source provided a nice sharp cut off line with adequate light intensity.

I could make do with any method but, for me, the monochromatic lite proved best for overall accuracy, especially when testing low birefringent stones. Any of the above methods work fine for a single standard reading.


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PostPosted: Tue May 22, 2007 9:04 pm 
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I do restaurant reviews too!


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PostPosted: Wed May 23, 2007 5:56 pm 
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Geez, hard to get a rise out of you guys. You don't like a little humor with your gemology?


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PostPosted: Wed May 23, 2007 6:53 pm 
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Next time try putting a bag of course salt on a bonfire. Now that should be bright enough. And if not you can dance and chant around the flames and confuse your neighbours...


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PostPosted: Wed May 23, 2007 7:00 pm 
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No thanks, I've already done 30 days for that. :lol:


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PostPosted: Wed May 23, 2007 7:08 pm 
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As long as there are some rocks in the prison courtyard for you to play with. Pieces of concrete just aren't fun.
Although you could always collect glass shards, mix them up in a crucible and when you get out, market it as "jailhouse moldevite" :twisted:


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