independent gemologist appraisal what to ask for???
- Thread starter scarleta
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Regular Guy
Ideal_Rock
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Between the first & second pages, there''s 3 substantive threads in the FAQ section here you may well want to look into.
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GIA has two locations.
One is in NY NY
The other is in Carlsbad California, near San Diego.
If you live nearby call them.
Make an appointment to take your GIA report and diamond to them yourself.
I did this and got a laminated letter of confirmation from GIA.
I dropped off the diamond in the morning and picked it up that afternoon.
It cost $75. (Or maybe it was $45, I'm getting old.)
Today I am more comfortable verifying a stone myself.
I have access to a measusing microscope, with dial micrometers on the stage, that is very accurate.
I also have access to a gemological scale to verify the weight.
If the weight and dimensions match the report, then it has to be a real diamond.
A CZ or glass cannot weigh the same and have the same dimensions.
A diamond has a unique density, which is weight for size.
Next if inclusions match the report you have a match.
There, that saves me some money.
You may get a local jeweler to weigh and measure the stone free if you consider having them set it.
Also jewelers and pawn shops have diamond testers.
One is in NY NY
The other is in Carlsbad California, near San Diego.
If you live nearby call them.
Make an appointment to take your GIA report and diamond to them yourself.
I did this and got a laminated letter of confirmation from GIA.
I dropped off the diamond in the morning and picked it up that afternoon.
It cost $75. (Or maybe it was $45, I'm getting old.)
Today I am more comfortable verifying a stone myself.
I have access to a measusing microscope, with dial micrometers on the stage, that is very accurate.
I also have access to a gemological scale to verify the weight.
If the weight and dimensions match the report, then it has to be a real diamond.
A CZ or glass cannot weigh the same and have the same dimensions.
A diamond has a unique density, which is weight for size.
Next if inclusions match the report you have a match.
There, that saves me some money.
You may get a local jeweler to weigh and measure the stone free if you consider having them set it.
Also jewelers and pawn shops have diamond testers.
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- Jan 11, 2006
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- 58,559
Richard Sherwood
Ideal_Rock
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- Sep 25, 2002
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I sometimes take flak for this, but my opinion is that when someone brings me a diamond for my "independent opinion", that''s exactly what I should give them. An independent opinion, which they can use in conjunction with any other documentation (major lab report, etc.) to base their purchase decision on or just have a better understanding of the gem they own.
Therefore I usually ask clients to let me do my analysis first, and then we compare my findings with any existing documentation they have. Any minor differences are usually understandable and easily explained, any major differences we go back and take a second look at, trying to get a feel for the reason why.
I tell clients "let''s say for example I grade the diamond as an "F" color, and GIA grades it as a "G" color. Then you know at the least that you have a very high "G" color diamond."
You see what I mean? It gives the client a better feel for the diamond. Most seem to appreciate this approach.
Therefore I usually ask clients to let me do my analysis first, and then we compare my findings with any existing documentation they have. Any minor differences are usually understandable and easily explained, any major differences we go back and take a second look at, trying to get a feel for the reason why.
I tell clients "let''s say for example I grade the diamond as an "F" color, and GIA grades it as a "G" color. Then you know at the least that you have a very high "G" color diamond."
You see what I mean? It gives the client a better feel for the diamond. Most seem to appreciate this approach.
I agree with Richard, but most of the time sellers send the reports to me.
If the customer is an in person one, it is their choice, whether I see the grading report first or not.
If it''s a long distance client, I can look at the report first, but even if I do, it isn''t going to change my mind from agreeing or disagreeing.
I also take 3-4 scans of it in the colorimeter, besides checking the stone against master diamonds too, in several positions.
I have had stones come in that are way off from their reports. Some stones come in that haven''t been graded by a major lab, and occasionally one that my eyes and the grading reports as compared to my eyes and the colorimeter I feel are better.
I suppose all appraisers with colorimeters or SAS machines do the same thing.
With Richard and David having the printouts from the SAS that substanciates gradings by an appraiser as well.
Rockdoc
If the customer is an in person one, it is their choice, whether I see the grading report first or not.
If it''s a long distance client, I can look at the report first, but even if I do, it isn''t going to change my mind from agreeing or disagreeing.
I also take 3-4 scans of it in the colorimeter, besides checking the stone against master diamonds too, in several positions.
I have had stones come in that are way off from their reports. Some stones come in that haven''t been graded by a major lab, and occasionally one that my eyes and the grading reports as compared to my eyes and the colorimeter I feel are better.
I suppose all appraisers with colorimeters or SAS machines do the same thing.
With Richard and David having the printouts from the SAS that substanciates gradings by an appraiser as well.
Rockdoc
Richard Sherwood
Ideal_Rock
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- Sep 25, 2002
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- 4,924
Date: 1/5/2007 9:59:31 PM
Author: scarleta
Thanks so much if you were closer I would definitely take the stone to you..I guess I have to make sure they have colorimeter or SAS machine ( whatever that is?) Many thanks..
This information is from Marty Haske's site, the developer of the SAS2000 spectrophotometer:
"The SAS2000 provides the most accurate colorimetry instrumentation available today for diamond color grading and produces a consumer oriented analysis which shows the WHY of a diamond color grade.
The SAS2000 combines a state of the art, dual channel fiber optic spectrophotometer with an approximate optical resolution of 1.5nm. The 400nm to 950nm band is quantified in approximately 0.3nm intervals, approximately 8 times finer than the next closest single purpose colorimeter. A DUAL channel system accurately tracks with the reference channel any variations in the illumination source spectra, in contrast to single channel colorimeters.
The SAS2000 is a high resolution system which utilizes GIA/GTL graded diamond master stones for its color grading calibration and a numerical grading system (0-10) consistent with the AGS colorimeter scale reading. Grading a diamond is a simple procedure which results in an estimated grade based on multiple mathematical comparisons from established color science theory as well as modeling of the visual grading process.
The SAS2000 additionally incorporates a special UV blocking filter so that color grading can be done without blue fluorescence influencing the grade."
You could contact Marty to see if there's an appraiser in your area with the SAS. His website is: [email protected].
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I also prefer to perform my own analysis first, without looking at the diamond grading report.
Any differences can be explained but usually a consumer wants an independent confirmation of
their purchase or pending purchase.
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