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 Post subject: Old GIA Spectroscope
PostPosted: Tue Sep 25, 2018 7:53 pm 
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Sorry, I posted this in the wrong place. I deleted it and moved it here.

Does anyone else have one of these spectroscopes? I have a lot of difficulty getting it aligned; it seems to be off to the right of center and tilts to the left. Also can't seem to get the scale to come into focus. It is rather wonky; I have to hold it by hand and gently move it left and right to get the spectrum to come into focus. When ever thing is lined up correctly, it works beautifully but can't hold the setting.

I have never been formally trained on how to use a spectroscope; this was given to me by an older man who got it from an even older man who was a stone setter and a GG. I don't know if it's been abused or if it again is a case of operator error. There are washers between the upright on the base and the arm for the spectroscope and fiber optic light; I'm wondering if they are not original and if that is what throwing things out of alignment. But the scale focus seems to be an independent issue.

Does anyone have any advice or a manual about how to operate or adjust this spectroscope? Part of the problem is I don't know how it is supposed to work and don't know anyone who has one; everyone else seems to use the OPL type.

Any help much appreciated.

Debbie K


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 Post subject: Re: Old GIA Spectroscope
PostPosted: Wed Sep 26, 2018 11:07 am 
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That was not built by GIA. It was built by Ted Themelis who may be able to help you sort out the issues.
Moving washers is the right track. Don't be afraid to take stuff apart carefully.

The scale focuses by moving the tube on the left in and out. you also focus the slit by moving its tube in and out.
The lit gem has to be in front of and casting light on the slit. The whole thing should be under a black cloth. Most gems want transmitted light so get that white stickum off.

Where are you located?


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 Post subject: Re: Old GIA Spectroscope
PostPosted: Wed Sep 26, 2018 4:54 pm 
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Thanks for the information. I'm in Houston, Texas. That area of white is the light from the fiber optic on a black background. I get more luck getting a good spectrum with light through the bottom than the reflected light method; but I always try to get a read both ways.

I'll try moving the tube in and out again; when it begins to be in focus the thing comes apart. I need to look at it a little more carefully, perhaps it is possible to move the entire mechanism up a little.

I didn't know that I should be using a cloth to block out other light, I'll definitely be giving that a try.

It seems like it's a really nice spectroscope, when everything is just right I get great lines and shadows. I use a triangle to get a good 45 degree angle and tighten things down, but the tilt to left and right is crazy-making.

Thanks again for your help.


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 Post subject: Re: Old GIA Spectroscope
PostPosted: Thu Sep 27, 2018 10:46 pm 
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The 45 degree angle is nice but especially doesn't matter much if you are using transmitted light.
You may need to change the positioning of the main tube so you can focus the scale. Or just don't even use the scale. They are often more trouble than they are worth.
The main thing is to only have light entering the slit which has been through the stone. Light that has gone around it is white light and will dim your spectroscopic features. This includes room light.


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 Post subject: Re: Old GIA Spectroscope
PostPosted: Fri Sep 28, 2018 6:44 pm 
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I had been told that they (the scales) were not necessary, more like a crutch, and that I should learn to work without them. But for someone new to spectroscopy, it can be helpful to find the general vicinity of a line.

I'll definitely be giving the cloth a try, I try to work in a darkened room, but I'm sure some daylight is seeping in.

There's nothing more gratifying to me than to see the jailhouse bars of a zircon or a pink cz when everything is working right! Which is why I want to get it working right all the time instead of some of the time.

Thanks again for your help.

Debbie K


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 Post subject: Re: Old GIA Spectroscope
PostPosted: Fri Sep 28, 2018 7:39 pm 
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Location: San Francisco
You may already have this link, Debbie K. I use it often.
https://www.geminterest.com/spectlist.php


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 Post subject: Re: Old GIA Spectroscope
PostPosted: Fri Sep 28, 2018 10:02 pm 
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Thanks Barbra! I was looking for this today and not finding it. I had it bookmarked on my last two computers, but not this one.

I have some cool color-change and color-shift synthetic sapphires and wanted to see if they had Vanadium, and remembered the French site and was thinking how useful this would be to see the spectrums.

Thanks again!

Debbie


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 Post subject: Re: Old GIA Spectroscope
PostPosted: Fri Sep 28, 2018 11:14 pm 
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I'm not sure Geminterest has it. Try
http://www.gemlab.co.uk/Synthetic%20col ... undum.html


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 Post subject: Re: Old GIA Spectroscope
PostPosted: Sat Sep 29, 2018 11:54 am 
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I have a spectroscope (well two, in fact, one by Beck and one by Zeiss) that look exactly like the spectroscope end of yours. I think that all the lights and holders are so much window dressing. I would remove the spectroscope from the holder, that should enable you to sort the adjustment, when you need to look at a spectrum, place your stone on a maglite or similar, with a doughnut of bluetack 1). to hold the stone in place, and 2). to exclude extraneous light. I can only see the fibre optic being useful when you are trying to get a spectrum from an opaque stone (jade and the like).


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 Post subject: Re: Old GIA Spectroscope
PostPosted: Sat Sep 29, 2018 12:08 pm 
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I kinda agree with Alan.
I have several hand held spectroscopes, in addition to a Beck.
I use the instruments with a fiber optic.
I view a stone with both reflected and transmitted light. I have found reflected light usually the most useful.

That being said, since I got the GemmoRaman, my use of hand held spectroscopes has taken a back seat.


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