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Refractometers

gemgirl59

Rough_Rock
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Jun 3, 2015
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I am taking a gemology course online and now need to buy a refractometer to continue and be able to test gems I buy from sellers outside of the well known, respected sources(not that they are shysters, just small time sellers or ones oversees in Indian, for example). I am working(slowly as I can afford things)on starting a little home business to supplement my disability income making some jewelry and selling some gems. I have been looking at the Presidium II that measures RI from 1-3., conveniently spitting out your RI number on a screen and then another one (the name escapes me at the moment) that tells you on screen what the gem is! Yes, they are several hundred dollars, compared to less than $100. for a traditional refractometer, but seems great convenience as I buy parcels.. I do realize the digital doesn't work on cabachons, but I rarely deal with those. Money is very tight for me, so keep in mind that it's not like I have lots of extra for what may be frivolous purchases. I welcome any input, comments or good resources to buy what may be recommended.
 

gemgirl59

Rough_Rock
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Jun 3, 2015
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Thank you, I found quite a few links through that thread with good resources to buy gemology items and a page comparing refractorometers!
 

PrecisionGem

Brilliant_Rock
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Jul 27, 2004
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I good refractometer costs more than $100. I don't think you will find any labs using the Presidium. It's more a tool that is used in Jewelery stores by people who are not really gemoligist. It's accuracy has been called into question often. I think you are better off getting a quality refractometer, and expect to pay $400 to $1000 for one that is accurate. Look for one with a built in sodium light source.
 

gemgirl59

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Thanks so much for your input. I am a home business trying to earn a little income to cover my health and practical needs as a disabled person. I am not a registered gemologist, but taking an inexpensive gemology program from International Gem Society to be able to assure customers that buy jewelry and gem stones from me, that what I sell is always geniune, mined OTG (out of the ground) natural gems. Integrity is paramount to me and I was glad to find this $400. IGS program that does cover everything, by is certainly not, nor does it imply, that it's program makes one a Graduate Registered Gemologist . The Gem-n-Eye III digital refractometer is concidered to be by far the best, most accurate digital Refractometer which contains a computer database of info to ID gems at your fingertips that can be updated from previous modals..... http://www.mineralab.com/Gem-n-Eye.htm,, a great SECONDARY tool. I will stick to a basic refractometer, as accuracy is my main goal and already have all the other tools to help with ID. ;-)
 

PrecisionGem

Brilliant_Rock
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If you go to my website, under Information is a Download page. There is a spreadsheet program that will assist you in calculating the optical character and other information from readings taken with your refractometer. It runs in Numbers on the Mac or iPhone/iPad, and is a free download.
 

gemgirl59

Rough_Rock
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Jun 3, 2015
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Wow, how cool....I will definitely download that, thanks for sharing that, giving me some much needed guidance and being a wealth of experience and information for me. I so appreciate this site and those so willing to advise! :razz:
 

bright&shiny

Shiny_Rock
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May 11, 2009
Messages
486
If you go to my website, under Information is a Download page. There is a spreadsheet program that will assist you in calculating the optical character and other information from readings taken with your refractometer. It runs in Numbers on the Mac or iPhone/iPad, and is a free download.

Is this still available? I saw another older post (more recent than this one, though) and checked your website and didn’t find a download section. I’ve got a lot to learn and every good tool helps:)
 

bright&shiny

Shiny_Rock
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May 11, 2009
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I will put that download back on the site in the next day or so.

You should consider this piece of software also:


Thank you! We had it on the list for our little gemological studio. We've been busy trying a DIY polariscope. It worked, but we are going to pick up a dedicated tool :)
 

PrecisionGem

Brilliant_Rock
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If you have a refractometer, and know how to really use it, you will find there isn't a lot of use for a polariscope. With the refractometer, and my spreadsheet tool, you can calculate the Optic Sign and Optic Character, and you will also know if the stone is single or double refractive, so there really is no use of the polariscope. I haven't touched mine in 10 years other than to clean the dust off it.
 

bright&shiny

Shiny_Rock
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May 11, 2009
Messages
486
If you have a refractometer, and know how to really use it, you will find there isn't a lot of use for a polariscope. With the refractometer, and my spreadsheet tool, you can calculate the Optic Sign and Optic Character, and you will also know if the stone is single or double refractive, so there really is no use of the polariscope. I haven't touched mine in 10 years other than to clean the dust off it.

Thank you and agreed. I’ve identified most everything so far with the refractometer and loupe.

This is for a specific mission: I am trying to detect if a “peridot” that refracts as sapphire is man made (it probably is).

@pokerface suggested we use the polariscope to find stria which would be definitive. We used a pair of sunglasses and improvised, but it was a pain. I’ll be posting the new images in the thread “definitely not a peridot”.

I appreciate hearing it’s not all that useful otherwise. I don’t like uni-taskers!
 

PrecisionGem

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Curved stria are difficult to see, and then only present in sapphire material that is made by the flame fusion process. Not sure that a polariscope would help you see these or not. Usually diffused light is used.
 

bright&shiny

Shiny_Rock
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May 11, 2009
Messages
486
@PrecisionGem - you could probably say that a hundred times and still not overstate it. It's a yellow stone, which seems to add to the challenge. I have posted a number of photos in the thread below - including those with the makeshift polariscope. I'm obviously new to this level of stone examination - but why not go for the gusto with a tough challenge? :geek2: I'm grateful for your posts - heading to your site now to see if the chart is there. Thanks again - you're a gem (pun intended)!

https://www.pricescope.com/community/threads/definitely-not-a-peridot.263128/page-2#post-4898463
 
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