It is with great sadness I'd like to announce Dr. Hanneman passed away on December 12, 2020. His legacy will live on forever!
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PostPosted: Wed Jul 26, 2006 11:03 am 
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What no one probably told you is that for some reason (I still don't quite understand why) the polariscope is useless on red stones.


Keep in mind that this guideline refers to red stones with RI's over 1.70 and OTL stones. This includes reddish garnets that can show ADR and be confused with ruby and spinel.

Lower refractive red stones like rubilite and andesine should be fine.


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PostPosted: Wed Jul 26, 2006 11:10 am 
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No one ever told me anything about red stones and polariscopes. I just looked at a series of red stones with the polariscope. Aside from ADR in garnets, all is as expected. Actually, a garnet's ADR is expected too.

I have a sequence of test I run on every colored gem.

It starts with the polariscope. Remember, each test is only a clue. Every time you use another instrument, you get additional clues.

One should never assume anything by only using one instrument.


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PostPosted: Wed Jul 26, 2006 1:02 pm 
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My polariscope cost me USD 7.50 and it works like a charm.
Just two sheets held together on an acryl rod I bought from Hanneman. Simply use the sky or an ordinary table lamp as illumination.
Another nice thing about it is that I can use it on my microscope to inspect interference figures.
One can also use it as a dichroscope (Hanneman ships them as two smaller polaroid sheets in the same package).
The spectroscope is your 5th instrument (eye and loupe first) to use on the OTL red stones.
CF is also a cost effective instrument (for chromium rich synthetics) as an additional test.
And let's not forget Visual Optics.

You can go a long way without the refractometer and a microscope, not all the way of course.

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Proud to be a DSN and JTV shopper, just love the guys!


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 Post subject: Thanks for polariscope help!
PostPosted: Wed Jul 26, 2006 10:00 pm 
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Joined: Fri Jul 21, 2006 1:11 am
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Location: Philadelphia area
Thank you all for the helpful suggestions! :D

Resting the stone on the lower filter sounds feasible (it almost seems as if I need three hands to work it otherwise). The light source is a small mag lite that screws into the bottom of the device.

I'm not experienced with gem photography yet, so posting a pic isn't possible at this time. But I appreciate the advice!

I'm happy to have discovered this group! :)


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