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 Post subject: Re: How to build a refractometer
PostPosted: Mon Nov 04, 2013 4:45 pm 
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The gadget on ebay is an OMAG battery lit magnifier. It sort of resembles a spectroscope with a scale.
As Dr. Bill said it is probably not too useful for gemology. OMAG is swiss so its' quality is not probably not bad. But it is probably a 20 or 30x pocket microscope.

I respectfully disagree with Dr. Bill. I think a microscope is useful even for identification. He is correct that you can use a loupe. And it is cheaper which is one of Dr. Bills' important criteria. But a microscope is much more comfortable to use and you absolutely do see more and spot things with binocular and stereoscopic vision and with higher magnification than what is available with the loupe. Using a loupe is an essential and fundamental skill. But if you can find a scope in your price range I would suggest it. (yes most scopes also don't fit in the pocket for field hunting and garage sale hunting)
No less a gemmologist than Basil Anderson referred to the microscope as one of the legs of the tripod of gemmology.


If you want to buy a spectroscope buy an OPL. It is the easiest to use. You don't need focusing or adjustable slits. (focusing can be handy if you have really bad eyes. but the OPL is an amazingly well designed instrument for its purpose) Dr. Bill used to carry those and I think Barbra may too.
DON'T be seduced by scale containing hand spectroscopes. The scales are mainly useless. The are usually not accurate unless you spend time calibrating them and even then you need to calibrate to the range you are looking for. And you need things to calibrate them with which most people don't have. And lighting and focusing the scale is an additional headache that most people don't need. Contributes nothing. With the opl you just point and look and make your observation with no instrument adjustments at all.
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Of course, as we both know, you actually have little interest in, or desire to, determine the RI, birefringence, and dispersion of OTL gems.

I don't know that at all. I don't have , at this time much OCCASION, or need, to make many such determinations. Because I continue to be employed , in a non gemology position. Where I spend all my time working with instrumentation. I am not quite sure why you would presume to speculate on my "interests and desires." There are other methods for determining OTL gems and I have a number of them in my personal collection which completely disproves your statement. Specifically I have one of the rare diamond table refractometers made by Rayner. I have two examples of the cubic zirconia critical angle refractometer , built in california in the 1980s. I also have a table spectrometer. (rather a pain to use, which I suspect the R-2000 is also , which is why I never built one from the instructions in the book.) and also an ellipsometer (which actually does work rather well for OTL measurements.) I also have a large collection of reflectometers including two of yours. They are largely a disappointment to me. (reflectometers generally, yours are neither better, nor worse, than the others. If something happened, that required me to keep only one reflectometer, I probably would select The Jeweler's Eye)

I also have accurate atomic wavelength sources(with interference filters since none of them are really monochromatic), and lasers, for determining dispersion, as well as water white polarizers, (which most people have never even heard of) for determining birefringence if I want to. I wonder if you have a functioning sodium light in your collection Bill.


I also disagree with Dr. Bill's statement that GIA s motive on instrument teaching and selection followed from a profit motive. Even though they charge a lot , often amounts even I considered too much , their expenses were probably high enough that I would be willing to bet that GIA did not make much money on their instruments. They were not working out of their den. They had employees and a physical plant and that all costs plenty of overhead to keep running. Their instruments were not built from scraps from the hardware store and modified consumer products.

There are a bunch of good techniques that they teach much less of then they might. Spectroscopy is one of them. They also used to teach Specific Gravity and they don't anymore because making and shipping specific gravity liquid kits got too expensive and they stopped letting people use the liquids in their twenty stone exams and classes because of OSHA regulations. They also don't teach as much about polarized light behaviour as they ought to. But in all these cases Dr. Bill , as well as others have stepped in to fill the void.


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 Post subject: Re: How to build a refractometer
PostPosted: Mon Nov 04, 2013 7:08 pm 
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Hello,

Thank you very much madame Voltaire. I appreciate. I will not tell the boys so they are going to have the surprise.

Mister Hanneman, I am looking forward reading your book. It seems so much interesting. And I think there will be some educational information for my boys. That is important to me.

I am really happy to have found this forum
Thank you everyone.

Brigitte


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 Post subject: Re: How to build a refractometer
PostPosted: Mon Nov 04, 2013 11:01 pm 
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We're happy you found us too. 8)


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 Post subject: Re: How to build a refractometer
PostPosted: Wed Nov 06, 2013 12:21 am 
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I respectfully disagree with Dr. Bill. I think a microscope is useful even for identification. ... No less a gemmologist than Basil Anderson referred to the microscope as one of the legs of the tripod of gemmology.

One must remember, Gemmology, as he used the term, is far different from simple gem identification. After all, Basil even used and recommended a microscope for mounting his spectroscopy studies.
On the other hand, Gem Identification uses NUMBERS, and as Lord Kelvin said, "Without numbers, one's knowledge of a material is of a meager and unsatisfactory kind." Microscopes do not produce numbers.
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If you want to buy a spectroscope buy an OPL. ... Dr. Bill used to carry those and I think Barbra may too.

As a matter of fact, Basil introduced me to the OPL and I purchased them from Colin Winter. I introduced them to the GIA and was their original source of supply.
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I also have a large collection of reflectometers including two of yours. They are largely a disappointment to me. (reflectometers generally, yours are neither better, nor worse, than the others.
If something happened, that required me to keep only one reflectometer, I probably would select The Jeweler's Eye)

Would that choice be based on the quality of instrument or the fact all other instruments have fictitious scales for RI which give the wrong answer as they do not factor in dispersion, or the fact my instrument produces a numerical value for luster of the facet, which has no relationship to RI but is useful for gem ID
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I wonder if you have a functioning sodium light in your collection Bill.

If truth be known, I got rid of my sodium light back in 1978. When I had finished my work on luster and adopted the Hodgkinson method for RI, birefringence, and dispersion, the critical angle refractometer was of no more interest to me.
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I also disagree with Dr. Bill's statement that GIA s motive on instrument teaching and selection followed from a profit motive.
Even though they charge a lot, often amounts even I considered too much , their expenses were probably high enough that I would be willing to bet that GIA did not make much money on their instruments. They were not working out of their den. They had employees and a physical plant and that all costs plenty of overhead to keep running. Their instruments were not built from scraps from the hardware store and modified consumer products.

Are you trying to say the GIA is not concerned with profit?
Granted, RTL was never considered up to date in gemological testing (witness his treatment for SG), however, everyone knew he was a superb business executive.
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There are a bunch of good techniques that they teach much less of then they might. Spectroscopy is one of them. They also used to teach Specific Gravity and they don't anymore because making and shipping specific gravity liquid kits got too expensive and they stopped letting people use the liquids in their twenty stone exams and classes because of OSHA regulations. They also don't teach as much about polarized light behavior as they ought to. But in all these cases Dr. Bill , as well as others have stepped in to fill the void.

Let me tell you about that void.
The void occurred when Basil Anderson died in 1985. In the teaching of gemology (GIA/GAGB or GemA), there was no one to take his place because either no one knew enough or cared enough. Effectively, the teaching of the classical fundamentals of gem testing progressed no further. Still today, no one is teaching anything newer than 1980, probably, because their teacher's were never taught anything new. That is because there has never been a "good" book about gem testing since Anderson's 9th edition in 1980. Later editions of B. Anderson and R. Webster books have been revised and those authors essentially ruined their values because they didn't know enough to properly evaluate the more recent approaches which they touted.


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 Post subject: Re: How to build a refractometer
PostPosted: Wed Nov 13, 2013 3:23 pm 
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Hello

I am very happy to tell you that I have just got the book "Guide to affordable gemology" off monsieur Hanneman. Madame Barbra has written last week that there was a surprise for my boys. They are not home yet and the surprise was for me. Thank you so much. It will be really helpful for me and the boys will be thrilled.

I have begun(or began?) to read the book. Big informations in there. As english is not my first langage, it is harder for me. I will take the time. I already incorporate some good informations. Physics was not my best subject at 17 years, even thought i would have liked very much to understand it and to like it.

Later, I will ask some help from you, people of the forum.

I see good expriments to understand more the principles of light. It will help me and be good for the boys. It always fun to do family stuff.

Thank you.

Brigitte


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 Post subject: Re: How to build a refractometer
PostPosted: Wed Nov 13, 2013 3:44 pm 
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Hello again,

Monsieur Hanneman has written that a microscope is not necessary. Monsieur G4lab thinks otherwise. For my part, I think that I will not resist to buy one!

I will not buy a new or expensive one. But I like microscopes. 2 weeks ago, I bought for my oldest a vintage Bausch and Lomb binocular microscope on eBay. He had already a vintage Meade but he asked for a binocular. I also bought a vintage little hand microscope for the youngest. He is interested by fossils, so he does not need big magnification.

So I will like a Vintage Gia microscope. I would probably buy eyepieces to enhance magnification. For the moment( for about 10 days), microscope are more expensive on eBay because Christmas is soon. I will wait. Last week-end, I almost bought a very old gem microscope. I lost by seconds before the end...It was really old as the objectives were like plates that you put under it. For the rest, it has all a gem microscope has. It was in my budget. For sure, if I would receive clients to sell, I would not have bitted on that one. LOL.

I know that I do not need a microscope as I do that for an hobby ( I do not sell). But, in my childhood, I always been around microscope and jeweller's equipment. I like that. It's fun.

Brigitte Lemieux


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 Post subject: Re: How to build a refractometer
PostPosted: Wed Nov 13, 2013 11:19 pm 
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Bonjour Brigitte,

The Motic ST-36 series has an inexpensive gemmological stereo microscope with darkfield and brightfield lighting, gem clip holders on either side of the stage and the gem clip that goes with it. Standard 20x - 40x magnification, but that could be upgraded with additional eyepieces. I paid somewhere in the vicinity of $350 -$450 USD for a new one in Bangkok about 9 months ago. I don't know what your price range is, but perhaps this falls within it.

http://www.motic.com/index.php

I don't see it in their catalogue (yet) but was told that it was a brand new product at the time, so maybe it's not yet been updated.

If you're in Canada, there is a Motic distributor in Vancouver that you could email and ask about it.

If you're in France, they have European distributors listed in Germany and Spain, although the guy who I dealt with in Thailand was a Brit and I was under the impression he sells them in the UK as well. I could dig out his contact details for you, if need be.


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 Post subject: Re: How to build a refractometer
PostPosted: Thu Nov 14, 2013 2:29 am 
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Brigitte wrote:
Monsieur Hanneman has written that a microscope is not necessary. Monsieur G4lab thinks otherwise. For my part, I think that I will not resist to buy one!

Just for the sake accuracy, I maintain a microscope "is not necessary for the purpose of gemstone identification", while Gene believes, "I respectfully disagree with Dr. Bill. I think a microscope is useful even for identification." Those two beliefs are not mutually exclusive. ("Not necessary for" does not equate to "useful even for.)
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I know that I do not need a microscope ... . But, in my childhood, I always been around microscope and jeweller's equipment. I like that. It's fun.

And that is the reason you should purchase one.

Now, if you want to really learn about gem identification, refrain from using a critical angle refractometer and use density, a dichroscope, and a polariscope. Of course, if one only wants the "name of the gem" or and its monetary value, get yourself a Raman Spectrometer and study appraising. :D


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 Post subject: Re: How to build a refractometer
PostPosted: Thu Nov 14, 2013 7:31 am 
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hi Brigitte,

have a look at these 2:

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... SS:IT:3160

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... SS:IT:1120

maybe the latter needs for a bit ow work...LOL..........but the price of the buy it now is really good......... :wink:

ciao
alberto

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 Post subject: Re: How to build a refractometer
PostPosted: Thu Nov 14, 2013 10:11 am 
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Hello,

So nice of you to answer me and help me!

To madame Julie

I live near Quebec city, province of Quebec, in Canada. I will look at the Motics. That would sound silly, but I prefer a vintage one unless the quality of the new one is better. I suppose that you are happy with yours as you recommand it. Thank you.


To monsieur Hanneman

I think that you are right. I have to learn the other instruments.
I saw in your book that you "loan" about 160 rough or loose gems for beginners like me that what to learn to identify. Do you still do that? I would like that very much.


To monsieur Alberto

Thank you very much. From Canada, the access to many american FB selling site are blocked because the saler asked so. That might explain why I did not see those, even I search via Google and eBay several times a day.
There are some american sellers that do not block canadian but write down that they do not sale to us. Most of the time, when I communicate with them and that we agree with the shipping cost, they agree to sell it. From what I understood, a lot of american sellers do not want to sell to us because it is too complicated because of the shipping and the customs. Shipping is higher to go to Canada. It seems also that some canadian do not know that their are probabilities that the item will go by customs hands and their evaluation. That takes time and cost the buyer more money. For my part, I am used to that and I always add the customs price to the item and consider the probable long delay before buying.
As you gave me the direct link, I have a direct access and I am noy blocked by FB. That is great!
Thoses prices are very good to me. The second one need a good cleaning but I do not mind. I bought lately an old diamonlite. You should have seen how it looked on FB and see it now. Big differnce. It is still old but it is clean! The second microscope is now at that bidding price but at the end, the probability are good that the price will be a lot higher. The first one is a fixed price. I think that I prefer the second one as it has 15x eyepieces. But I might buy the first one. It will depends on the final price of the second one.
My husband offered to give me that for Chrismast. I thought that I will not be able to find one. Now, it seems possible!
So thank you very much.


Brigitte


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 Post subject: Re: How to build a refractometer
PostPosted: Thu Nov 14, 2013 11:09 am 
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Hello again,

I read back some old posts over the forum. Once monsieur G4Lab duplicate an advice from "Absolute clarity". In there, they were saying to avoid the Mark IV and the Mark V.

As I am an hobbyist and the price is good for me( around $475 USA with shipping and customs), do you think that I can buy it without regretting it?


Thank you.

Brigitte


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 Post subject: Re: How to build a refractometer
PostPosted: Thu Nov 14, 2013 7:11 pm 
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Brigitte wrote:
As I am an hobbyist and the price is good for me( around $475 USA with shipping and customs), do you think that I can buy it without regretting it?

No. :D :D As I see it, you presently don't have the slightest idea of how to use a microsope for gemology or what you want to do with one, except to see better. However, you have no idea of HOW MUCH better you need or desire.

Learn to use a 10X loupe or even get a 20X loupe to ascertain what your actual requirements are, or your desires are, before you should even begin to try to pick out a microscope which will leave you with no regrets.

Send me your mailing address and I will resolve your other questions.


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 Post subject: Re: How to build a refractometer
PostPosted: Sun Nov 17, 2013 12:38 pm 
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Hello,

Finally I did not resist. I have bought the first microscope that monsieur Alberto had found earlier. It is my husband's gift for Christmass. I am happy about that.

I communicated with the saler and he is adding a Bausch and Lomb 15x WF eyepieces with a 2x auxiliary for the objective. The last one has a little crack in it. I have to see first where it is before knowing if it will be usable.

From my point of view, it is a good price. Later, if I change my mind and want something else, I do not thing that I will lose a lot by resaling it. By that time, my boys and I will enjoy it.

I still want to learn how to use a 10x magnifier. I have one of my late mother. It is a Ruby and son triplet 10x 20.5 mm. It has about 30-35 years. It is in very good condition as my mother took very good care of her things.

I have some diamonds at home and other precious gem. They are all mounted. Can I start my training with the magnifier with those?

Brigitte


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 Post subject: Re: How to build a refractometer
PostPosted: Sun Nov 17, 2013 1:09 pm 
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hello Brigitte, best wishes for your new microscope.
first thing i would do is to change the lamp setup, those are discontinued, no longer produced. it would be ok to change the system to halogen, be careful not more than 20 W otherwise your Darkfield well will get really hot....... :wink:
ciao
alberto

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 Post subject: Re: How to build a refractometer
PostPosted: Sun Nov 17, 2013 1:55 pm 
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Hello,

By discontinued, do you mean that I can not find bulbs to continue to use it? How do I replace it?

Of course, it is supposes to light on now. Maybe I have some time before it goes off.

Brigitte


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