CIBJO releases Gemmological Special Report: considers process of separating measurable facts from opinion; See Gemological Articles below.
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 Post subject: Re: Tutorial on Using a Reftactometer
PostPosted: Thu May 22, 2014 10:40 am 
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Like everything, it takes some practice.
Consider working with known samples.
Like amethyst.
Get a 5mm, 3mm and see how you have to bob your head to get the proper readings.


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 Post subject: Re: Tutorial on Using a Reftactometer
PostPosted: Fri May 23, 2014 5:42 am 
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The stones I am looking at under the refractometer are 3x5mm pear shaped amethyst and a 3x5mm oval synthetic blue spinel.
I'll try in a darkened room next.

The amethyst set in a ring that I did get a reading from was about 20mm square.

As a matter of interest, should the glass on the refractometer be level with the metal surround? Mine is a touch higher which makes sliding the stone onto the glass a bit difficult.


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 Post subject: Re: Tutorial on Using a Reftactometer
PostPosted: Fri May 23, 2014 10:38 am 
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Usually German refractometers have a raised hemicylinder.
Purpose?
To be able to test prong-set gems.


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 Post subject: Re: Tutorial on Using a Reftactometer
PostPosted: Tue Dec 02, 2014 7:38 am 
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That's great information but i have not understand properly what is the real use of refractometer from your point of view.


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 Post subject: Re: Tutorial on Using a Reftactometer
PostPosted: Tue Dec 02, 2014 1:50 pm 
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To determine the refractive index of something.


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 Post subject: Re: Tutorial on Using a Reftactometer
PostPosted: Fri Dec 05, 2014 3:22 pm 
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Barbra Voltaire wrote:
To determine the refractive index of something.

To determine what a stone cannot be because its RI is not right.


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 Post subject: Re: Tutorial on Using a Reftactometer
PostPosted: Wed Feb 11, 2015 12:33 am 
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Very true on the last post. Pretty much any gemological tool allows you to use deductive reasoning. As stated in many gemological texts, such as "Atlas of inclusions 1".

You cannot use a inclusion (and in this case any gemological finding) to prove that a stone is in fact 100 percent, without a doubt the suspected material.

You can only use a inclusion to rule out certain possibilities, liken the chance of your hypothesis with other gemological testing.

There really are no absolute ways of determining gemstone variety or origin to the gemologist with less than say 100,000 dollars of lab equiptment.

Each gem is different in regards to natural vs synthetic. Many processes can give a result of gemstone. Whether it is natural or syntethic will always be tricky, as new processes of synthesis can evolve everyday.

Through the full use of all gemological tools available, staying up to date on successful synthesis processes, strange reportings/properties/prices/origin rumor/ one can be as accurate as possible in making these decisions.

Even lab results, do not technically prove a thing. As oversight, calibration, physical evidence and oversight of the testing, etc........can not be 100% seen.

Not to say that the GIA's word isn't fact!

But nearly to say, that any statement can be justly be argued true or false.

You change syntax, logic, choice of vocabulary, order of words to pursuey your hypothesis, but any statement can be turned false.

Example:

Presumed true statement:
The sky is blue

Revised statement:
The sky cannot be blue, because blue is a color produced by your brain. Without a human brain, there is no colors.

Next statement presumed to be true:
1+1=2

Revised falsified version or argument
1+1 is a set of three characters. Unless one fully explained how to write a mathematical equation, and told the proper syntax of expressing mathematical theories directly previous to the statement 1+1 I would have no idea what they are talking about. To me 1+1 looks like artwork. To many 1+1 may indeed =2, but those people are crazy and have been influenced by mathamatics teachers. I am not a mathematician, but a artist. Therefore 1+1 is simply art. Anything before your eyes is simply art, no fact therefore unless a quite convincing set of logic was presented to me.

Next presumed true statement:
My name is $$$$$$$$$

Revised
Since I named you %%%%%%%%, your name is %%%%%%%%%, not $$$$$$$$$$$$$. Unless you were to be more specific as to what name you were referring to............

etc...........

on
and
on
forever times infinity.

There is scientific fact, and there is always a way to argue scientific fact.

anyways, hope you don't make any judgement errors in your gemological quests.


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 Post subject: Re: Tutorial on Using a Reftactometer
PostPosted: Wed Feb 11, 2015 12:53 am 
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Also, thanks a lot Starla, and Barbara for the link. It can take some time to fully understand some things in gemology, such as how light interacts with stones. Since just understanding light, how humans perceive color, shapes, what goes into achieving maximum brilliance and fire can take a while.

But using other things I've studied such as light interaction, things can now fully make sense. I like how she said that it really could be called something else, as that clarifies things a little more.

It isn't as simple to use as some other tools are such as a calipers. The reading could be flawed because of air. Which is the reason for refractive lquids.

Using what I know about snell's law, you would know that air itself has a refractive indice.

So, even fully understanding what you are doing when you use a refractometer can take some time, and may take many resources and wordings and explanations from various authors. A lot of things in gemology do not make sense to me until I a see another persons explanation. You need as many resources as you can, and apply them in your own notes, diagrams, flowtrees, pictures, tables, databases, charts and graphs. But taking a class can accelerate this learning. But if you took the class, and say didn't know that air has a refractive indice, then that may not make sense. So, there is a right time to take classes, and the time is different for everyone with different goals. Personally, I tend to think about the wrong things, and obsess about external factors to the classes, thus making books and all other resources more feasible at the time.

ANywho, it's nice that things are clicking and this is a wonderful resource that I gotta process, write my quizzes, make diagrams, and make sure I apply to understand. It sure is not a definitive resource to determine which refractometer is the best quality, for the best value, for your specific budget though. Shopping decisions regarding tools cannot be made by buying kits, or turnkey "how to be a professional gemologist packages!"


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 Post subject: Re: Tutorial on Using a Reftactometer
PostPosted: Sat Mar 07, 2015 1:58 pm 
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Video is very helpful ,thanks.


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 Post subject: Re: Tutorial on Using a Reftactometer
PostPosted: Mon Mar 23, 2015 9:20 am 
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Wow! I love the tutorial. Looks like I have more equipment to buy.


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 Post subject: Re: Tutorial on Using a Reftactometer
PostPosted: Sat Aug 15, 2015 5:22 pm 
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We use 1.81 for our needs, why all the other wts. of RI fluids?
or do we use them also for specific occasions?

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Dan


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 Post subject: Re: Tutorial on Using a Reftactometer
PostPosted: Sat Aug 15, 2015 11:16 pm 
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RI liquid measuring 1.81 is hard to get......something about toxicity as I understand it.


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 Post subject: Re: Tutorial on Using a Reftactometer
PostPosted: Wed Nov 11, 2015 4:36 pm 
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Barbra Voltaire wrote:
RI liquid measuring 1.81 is hard to get......something about toxicity as I understand it.


seems to be relatively easily found on ebay ... noting issues with toxicity


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 Post subject: Re: Tutorial on Using a Reftactometer
PostPosted: Thu Nov 12, 2015 12:37 am 
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Fair enough. I don't buy RI liquid on eBay so never checked.


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 Post subject: Re: Tutorial on Using a Reftactometer
PostPosted: Tue May 17, 2016 1:50 pm 
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Question about refractometer (as opposed to "reftactometer" :wink: ) and facet rough. I read that you cannot test facet rough for R.I. with refractometer but are there any conditions where it may be possible? For example, would it be possible with 1 flat, polished surface or maybe 2 flat, polished surfaces (180-degrees from each other on the stone), etc?


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