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Learning to use the conoscope


#1

Feeling really self conscience about asking for help in the forum, but somehow I’m totally at a loss as to how I’m supposed to use the conoscope. I don’t have the glass sphere type, but the wider flatter turnable plastic type. I can’t figure out how to “focus” it. I can’t find anything remotely like an optic sign.

I guess it’s certainly possible that the light source to my cheap handheld polariscope is to blame, but are there any tips for using this infuriating little device? Thank you


#2

Okay…
I’m guessing this wasn’t a very fair question

Don’t worry, I’ll figure it out


#3

This is one of the best descriptions that I’ve seen. It has been a long time since I’ve used one so better to give you this. I’m just getting back to a love for gems. Read down to the explanation at the end of the article.

http://www.gemologyproject.com/wiki/index.php?title=Polariscope


#4

Thanks for the reply Aleta!
I’ll have to try submersing the stone to get a stronger interference pattern.


#5

Come back and give us an update. Sometimes it takes a little time to get a reply on here. I think the man who ran it before either retired and sold it or passed away and they are trying to re-establish it. It seems to be getting busier litle-by-little. Return and start participating. Even if you are a novice, like me.


#6

Sorry for the late reply gemw. I’m on the site a lot, just not the forum…and never noticed there was a little icon in the corner telling me about your reply ._.

I’ve gotten much better at finding optic signs! It was a matter of just practicing and persisting in looking in every corner of a gem (and making sure to use a loupe!) The magnification makes a huge difference in being able to see the interference colors. Now if only I had a third arm to hold everything…

I’ve finally seen real Brazil-law twinning in some quartz pieces I have too. The abrupt, geometric shaped interference is quite unique…but are there different patterns? I’ve noticed the amethyst pattern looks different from the pattern on my bi-color smoky quartz piece.


#7

What did you do to make it easier to see the color flash? I cant see it.


#8

Just take your time. Use good magnification. And remember that not all gems are going to show interference.
What sort are you using to practice with? How are they cut?
The colors show up around the optic axis of a stone, so a lot of times you can see it through the girdle or long axis of a cut stone. If it’s an issue of not being able to see what’s going on inside because of all the reflections, submerse it in water or oil and all the exterior reflections will be masked.
Also, I recently found these two resources online that explain a lot about how this stuff works, I haven’t read in depth but I’ve learned a a lot
http://www.gemstones-guide.com/Identification-by-Polariscope.html
https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/learn.php