charlessand
Rough_Rock
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refractometer
- Thread starter charlessand
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Date: 5/16/2005 5:09:11 PM
Author:charlessand
Hi,
Can anyone help me out with this little problem. How do I read the scale of a refractometer? The scale grades from 150 up to 180. The refr. index of diamond is 2,417, how do I read this on the scale????
The limits of the refractometer are exactly what you wrote.
A refractometer is not useful for identifying diamond or other stones with high refractive indices.
The refractometer is an extremely useful too for identifying gemstones with R.I''s with the limits of the machine.
If you are trying to identify that the stone is a diamond, there are varied tests you can do. But if you know you have a diamond, then you certainly don''t need a refractometer.
The refractometer is primarilly a tool for identifying a gem material. It is NOT a grading tool, per se.
Tell us what you are trying to accomplish and I''ll make some suggestions for you.
Hope this helps.
Rockdoc
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I see that you are Valuers of art, diamonds and jewellery.
http://www.puig-sand.com/
How can that be Charles?
You can do what you need to do with a heat conductor tester that discriminates between all imitations, Mosissonite and diamond.
Search for Moissanite testers.
But probably the first thing you need is a gemology course - HRD and IGI run them in Antwerp - not that far for you to go.
http://www.puig-sand.com/
How can that be Charles?
You can do what you need to do with a heat conductor tester that discriminates between all imitations, Mosissonite and diamond.
Search for Moissanite testers.
But probably the first thing you need is a gemology course - HRD and IGI run them in Antwerp - not that far for you to go.
strmrdr
Super_Ideal_Rock
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charlessand
Rough_Rock
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Hi,
As usual, things are more complicated then they seem. Problem is I have to value a big rough stone, appr. 250 cts. A small top has been taken of by laser sawing, from which the table has been polished.
I do have a strange feeling about the stone. I have worked for many years in the diamond trade, have been a diamond cleaver, and my parents and grand parents where diamond manufacturers. I am only saying this to explain that I have manipulated a large amount of diamonds, rough and polished.
I left the large stone with the owners an took the "top" to my office. According to GIA it is a massive cryptocristalline variety of diamond. W.T.O.C.D. (approved by HRD) say that the specific gravity was determined to be 3.52g/cm3, beeing the s.g. of diamond.
The large stone is to opaque to measure tension with a polariscope. The hardness is 10 on Moh''s scale.
So this is the problem. My only doubt is subjective because based on a feeling. This is why I was thinking of a refractometer, because the table of the tope is polished, (on my demand).
Any suggestions???
As usual, things are more complicated then they seem. Problem is I have to value a big rough stone, appr. 250 cts. A small top has been taken of by laser sawing, from which the table has been polished.
I do have a strange feeling about the stone. I have worked for many years in the diamond trade, have been a diamond cleaver, and my parents and grand parents where diamond manufacturers. I am only saying this to explain that I have manipulated a large amount of diamonds, rough and polished.
I left the large stone with the owners an took the "top" to my office. According to GIA it is a massive cryptocristalline variety of diamond. W.T.O.C.D. (approved by HRD) say that the specific gravity was determined to be 3.52g/cm3, beeing the s.g. of diamond.
The large stone is to opaque to measure tension with a polariscope. The hardness is 10 on Moh''s scale.
So this is the problem. My only doubt is subjective because based on a feeling. This is why I was thinking of a refractometer, because the table of the tope is polished, (on my demand).
Any suggestions???
Perhaps some more intense microscopic examination is called for.
This is difficult because we can''t see the image of the item. You might want to examine to observe trigons if any.
Is the stone so opaque that polishing more windows wouldn''t lead to anything conclusive? If the stone is very opaque it may have an alternative value other than the value based on polishing it. 250 carats sounds unusually large, so it could have a value as a crystal/ mineral/ which of course is a different market than the assumed one of cutting.
You could also examine any fractures and analyze them as that could be helpful.
I realize your are attempting to make conclusions based on your gut feeling, due to previous experience. But you didn''t explain specifically what those gut feelings are. In that we can''t see it, I guess we have to depend on your visual observations and initial gut feelings. Do you think its been subjected to HPHT treatment?
Since I can''t see it, perhaps, I might suggest it be tested using the diamond sure, D Screen etc. or short wave / long wayve ultravioet under magnification or Raman testing.
Rockdoc
This is difficult because we can''t see the image of the item. You might want to examine to observe trigons if any.
Is the stone so opaque that polishing more windows wouldn''t lead to anything conclusive? If the stone is very opaque it may have an alternative value other than the value based on polishing it. 250 carats sounds unusually large, so it could have a value as a crystal/ mineral/ which of course is a different market than the assumed one of cutting.
You could also examine any fractures and analyze them as that could be helpful.
I realize your are attempting to make conclusions based on your gut feeling, due to previous experience. But you didn''t explain specifically what those gut feelings are. In that we can''t see it, I guess we have to depend on your visual observations and initial gut feelings. Do you think its been subjected to HPHT treatment?
Since I can''t see it, perhaps, I might suggest it be tested using the diamond sure, D Screen etc. or short wave / long wayve ultravioet under magnification or Raman testing.
Rockdoc
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I'm confused with what you are trying to determine. Are you suspecting that a 3.52 SG, hardness 10 object is made of something other than diamond? RI won't tell you if it is natural origin or if it's been treated.
Neil Beaty
GG(GIA) ISA NAJA
Independent Appraisals in Denver
Neil Beaty
GG(GIA) ISA NAJA
Independent Appraisals in Denver
charlessand
Rough_Rock
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Thanks for your reply.
I do think the stone is diamond, but the structure of the stone is very strange. Totally opaque dark grey, with "veins" running in it, never seen anything like it before. As I can''t determine if there is any tension with a polariscope, I am really confused concerning the risk during the sawing and polishing process.
I do think the stone is diamond, but the structure of the stone is very strange. Totally opaque dark grey, with "veins" running in it, never seen anything like it before. As I can''t determine if there is any tension with a polariscope, I am really confused concerning the risk during the sawing and polishing process.
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charlessand
Rough_Rock
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well, I asked a polisher to try this, and after 2 hours he came back telling he did not want to damage his disk,
the way the owner of the stone wants to proceed, is to cut (saw) with laser the facets and then to polish them, process will be of ± 6 months,
if you are interested, send me your email adress and I will send you a picture of the small "top",
the way the owner of the stone wants to proceed, is to cut (saw) with laser the facets and then to polish them, process will be of ± 6 months,
if you are interested, send me your email adress and I will send you a picture of the small "top",
Richard Sherwood
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JohnQuixote
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belle
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a friendly 'net' reminder...
you should not post your email address publicly in it's normal format. if you post this way, it can be read by web crawling spy bots that spammers use to add email addresses to their massive distirbution lists.
if you need to post your address publicly, you can use words instead of the symbols.
[email protected] would be: richATexampleDOTcom or rich(at)example(dot)com
you should not post your email address publicly in it's normal format. if you post this way, it can be read by web crawling spy bots that spammers use to add email addresses to their massive distirbution lists.
if you need to post your address publicly, you can use words instead of the symbols.
[email protected] would be: richATexampleDOTcom or rich(at)example(dot)com
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I have a friend in India who has a state of the art 5 axis laser facet blocking facility.
There is something about it here
http://journal.pricescope.com/Articles/19/10/Diamond-Adventures-in-India.aspx
There is something about it here
http://journal.pricescope.com/Articles/19/10/Diamond-Adventures-in-India.aspx
charlessand
Rough_Rock
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charlessand
Rough_Rock
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