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Multiple Certifications

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Kelb_Kabeer

Rough_Rock
Joined
Jan 6, 2003
Messages
2
I have seen multiple certifications and am wondering which ones have the better reputations. These are the ones I have seen:
AIG- American International Gemol.
IGI- International Gemological Institute
GIA- Gemological Institute of America
EGL- European Gemologcal Lab
PGS- Professional Gem SOciety
AGS- Americal Gem Society

Could somebody who has an idea rank these insome order based on the reliability of the certifications please. Thank You.:bigsmile:
 

Richard Sherwood

Ideal_Rock
Joined
Sep 25, 2002
Messages
4,924
I would rank them as follows:

1A: AGS- Americal Gem Society
1B: GIA- Gemological Institute of America

2A: PGS- Professional Gem Society (Professional Gem Sciences, Chicago)
2B: EGL- European Gemological Lab (If it's the NY, LA, or Antwerp lab)

4A: IGI- International Gemological Institute

AIG I'm not familiar with. Let me know if you get more feedback on them.

Rich, Independent GG
Sarasota Gemological Laboratory
 

DiamondOptics

Shiny_Rock
Joined
Jun 27, 2002
Messages
380
I would rank them as follows:

1A: AGS- Americal Gem Society
1B: GIA- Gemological Institute of America

2A: PGS- Professional Gem Society (Professional Gem Sciences, Chicago)
2B: EGL- European Gemological Lab (If it's the NY, LA, or Antwerp lab)

4A: IGI- International Gemological Institute



Hi Richard, :))

Can you give me the symmetry results for those
certs. :bigsmile:

And what do you think the polish might be
on those reports.:cheeky:

Kirk
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
14,929
EGL USA is far stricter than EGL.

GIA have really gone off. I have dealers telling me more than 1 clarity grade away is not uncommon. Empolyment and retaining trained staff has always been a big problem for them, since anyone leaving can tell the world they have worked as an Arch Angel.

I have also heard that IGI has recently become very strict, although I have yet to see evidence. An October 2002 stone looked way off to me.
 

Architect

Rough_Rock
Joined
Dec 11, 2002
Messages
35
Cut Nut,

It came as quite a shock to read your comments about GIA grading, especailly since I had searched for a diamond for 5 months before I finally decided to buy one and never did I hear one bad word about GIA from any of the diamond dealers or experts. In those 5 months, I have become extremely familiar with diamonds through extensive research and so I consider myself fairly knowledgable on the subject for a non-expert.

I'm sorry, but for you to say that you have dealers telling you that a difference of more than 1 clarity grade on GIA certified diamonds is not uncommon seems a little absurd to me. How are these dealers determining that these diamonds are off in clarity, is it their opinion after inspecting the diamonds? Do those remarks come from several different dealers in different areas? Never have I read on this forum, or anywhere else for that matter, that a GIA certified diamond was off in clarity or color from what it was graded. Perhaps some of these dealers are trying to endorse EGL or other grading labs because those are the certified diamonds that they have and sell. I have found that the dealers who try to talk down GIA certified diamonds are the ones that do not carry any of them. Maybe another explanation is that the source from which these dealers are getting their diamonds from is possibly switching diamonds and certificates. For example, how can a diamond that is GIA certified to be a VS1 turn out to be SI1? There are several guidelines for grading that determine clarity such as number of inclusions and size of inclusions so to be off by more than 1 clarity, especially from GIA, is just plain nonsense. Do you have a list of the dealers that have given you this information?

In regards to GIA not being able to hold onto it's staff, I don't see how that has anything to do with the quality of grading diamonds. All labs have guidelines for grading and when they train people, they follow those guidelines to remain consistant. The staff that gets trained and stays with GIA follow very strict guidelines when grading. If people leave that lab, they are not effecting the grading process since the grading is not imposed upon one person, but several to check the diamonds and make sure they are the clarity and color that is specified in their certification.

Cut Nut, I am offering my opinion on your comments only because anyone that reads them might interpret it as you saying that GIA has somehow gone from a very strict grading lab, to one that is mediocre at best. GIA is the strictest in it's grading, and until someone comes along with proof rather than word of mouth, it will remain to be so. Have you personally ever come across a GIA certified stone that was off in clarity or color? Years ago, EGL was less strict and it was proven several times when certified diamonds from that lab would get sent to GIA and come back as a worse clarity or color grade...the same would have to be done with a GIA certified diamond before anything bad can be said about that lab. The only lab I would trust to do as strict of a grade on a diamond as GIA does is AGS, although HRD has been establishing itself as a very trustworthy and strict lab also.

Once again, my comments have been offered as the opinion of a non-expert since I do not work in the jewelry industry. I have found that this forum is an excellent source of information for people trying to get educated on diamonds before they buy, as long as the information remains to be provided from facts, or at least verified by several experts. :read:
 

ready

Rough_Rock
Joined
Sep 23, 2002
Messages
77
I have to agree with CutNut because I saw it firsthand. I was comparing two GIA graded diamonds in a diamond grading trough at a dealer - both graded "G" per certifications. One was significantly more tinted the the other...these stones were both rounds, both 1.25 carat area. Obviously, one of the diamonds was misgraded. I performed this same exercise (two like-graded GIA stones of similar weight) at another dealer as well, with the same results. Even compared them to master CZ's. k I also saw a GIA VS2 stone with an eye-visible fleck of carbon in the table. It looked worse than some SI2 EGL's I saw. Like you, I was shocked since everything I'd heard on this board and other venues touted GIA as one of the more consistent grading lab.

It was at this point that I threw out the notion of buying a diamond based on grading reports. It would have been a mistake for me to do so. I opted instead to purchase one from a degreed gemologist who had the proper equipment in-house to determine light return, etc. Foremost, I purchased one that was beautiful to my eye. In my diamond search experience, I became disenchanted with all of the grading labs. In fact, the one that seemed to reflect the least inconsistencies seemed to be.....drum roll please......IGI.

I'm not a gemologist by any means, but I can tell the difference between the colors of two stones in a grading trough...and can see when there's a piece of Kingsford right in the middle.

I wouldn't have brought this up, but I witnessed it on a few occasions. In other words, none of them seem extremely consistent to me. I think this is why it is of paramount importance to get the thing checked out and deal with those you trust.
 

Serg

Ideal_Rock
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Mar 21, 2002
Messages
2,472
----------------
On 1/7/2003 10:32:12 AM

There are several guidelines for grading that determine clarity such as number of inclusions and size of inclusions so to be off by more than 1 clarity, especially from GIA, is just plain nonsense.
----------------


It is not true for GIA.
HRD has similar system. GIA Grading strong depends from expert professional skill and a several other causes and technologies.
Do you know all reason Why GIA use Horizon system?
 

optimized

Shiny_Rock
Joined
Dec 28, 2002
Messages
306
I would also like to chime in here, just to throw a word of caution into the mix, and to plead for input from some more folks around the forum. Like Architect, I was shocked to hear Garry's comments about GIA certifications, and even more shocked to hear others agree with his assessment. In fact, Architect basically covered all of the points I would make, so I would just like to reinforce some of them.

In my months of learning about and searching for a diamond, I read countless opinions about grading labs, and without a doubt there were two labs that were consistently cited as the "most trustworthy" for diamond grading: GIA and AGS. My impressions of the endorsements basically made me think that the GIA definitely and demonstrably has the most unimpeachable reputation for grading, and that AGS, while perhaps not quite as consistent (but still very reliable), offered the benefit of more complete information (cut ratings and crown/pavilion angles, etc.), which made them attractive to many people and respected within the industry.

My various readings seem to indicate that the trustworthiness of the GIA, having to do with their status as a not-for-profit "educational" organization not influenced by industry forces, their use of technology in conjunction with trained human examiners, and their collective practices of using a sort of "double-blind" consensus system to ensure that no one grader's opinion would solely determine the grade of a diamond, made them remarkably consistent. I had never (ever) heard a single negative word about GIA certification until this thread popped up, and just going by my ravenous consumption of everything diamond-related, it's hard for me to believe that something wouldn't have crossed my radar before now.

I can't help but wonder, as Architect pointed out, whether some people who may be saying GIA has become inconsistent are falling victim to comparisons of diamonds that have been switched by some nefarious individuals out there, or have some other agenda that they are trying to promote. Ready pointed out an eye-visible fleck in a GIA-graded VS2 diamond he saw while shopping, which just seems patently absurd to me. I don't doubt Ready's word, but I do wonder whether he was actually being shown a different stone than the VS2 he was told, or whether some other dishonest practice was being perpetrated by the seller (or even some honest and unfortunate mix-up occurred). Similarly, I wonder if the difference in color he observed had anything to do with a dealer attempting to sell a more expensive stone, or some similar motivation. As of right now, I trust the GIA much more than many dealers.

Being at the top opens any organization up to criticism, and I am left wondering whether these new accusations of the inconsistency in the GIA is the result of being so respected for so long. There are a number of people who would like to see the GIA's reputation crumble, from dealers who sell diamonds graded by some of the more generous (and cheaper) "dealers labs" that are also often mentioned, to competing labs who seek to lift themselves out from under the rather large shadow cast by the GIA's reputation. There are certainly a whole lot of people who would like to see the GIA's image tarnished, to be sure, but I can't help but think the GIA is sensitive to this and does all it can to ensure its practices keep it at the top of the heap.

Some minor inconsistencies in any subjective grading system are to be expected, especially in a system with such remarkably fine distinctions between grades, but this new take on the GIA is a really shocking bit of information to me. I would like to hear more comments from the great folks here in RockyTalk about it, and I'd especially like to hear some more on this topic from Garry since he is such a frequent and respected contributor to the forum. If GIA certification is starting to lose value, we should all know about it. On the other hand, if there are folks out there whose experience seems to run contrary to this new notion, I hope they will take the time to write here as well. The diamond industry, being a business that is so often maligned (from outside and within) as being populated with hearty helpings of deceit and ignorance right along with the honest and knowledgeable, has an interest in having reliable organizations exist to help anchor the boat against the forces that would seek to turn it into a schemers' free-for-all. For me, the GIA has consistently been referred to as one of the true seekers of reliability and stability in the industry, and I hope that isn't changing. If it is, I can only imagine the world of gemology will suffer as a result....

-Tim
 

ready

Rough_Rock
Joined
Sep 23, 2002
Messages
77
I agree that there's a lot of less-than-honest dealers out there. I wouldn't discount that I encountered some in my search. However, the odds that I saw discrepancies at more than one location, and that the similarly sized and graded stones were also similarly priced, I doubt this was causation.

I think to blindly accept any lab's word as gospel is foolish, unless you don't care what you're getting. I saw EGL stones that looked wonderful for their grade, in terms of color and clarity(exceptional SI1 and 2s) and GIA stones that looked horrible for their respective grades. Vice versa as well. My point here is that (in the limited experience of my personal search - 4 months and probably 100 diamonds viewed) I would not and did not put money on any lab's grading report as my primary purchasing criterion. My search proved to ME that none of them consistently held water.
 

Serg

Ideal_Rock
Trade
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Mar 21, 2002
Messages
2,472
I think , anybody has right read and distribute information like below.
I think it is helpful for health of diamond market:
"

September 16, 2002

Consumer Response Center
Federal Trade Commission
600 Pennsylvania Ave, NW
Washington, DC 20580

REFERENCE: Verbal Complaint #2312420 File September 13, 2002

Complaint Against :
GIA Gem Trade Laboratory
A Wholly Owned Subsidiary Of The Gemological Institute Of America
5355 Armada Drive
Carlsbad, CA 92008-4699

1) The subject of this complaint is the GIA Gem Trade Laboratory's use of the word "NONE" in a manner that results in deception and financial harm to dealers and the public, who rely on such descriptions, as explained below in this complaint. They consistently use "FLUORESCENCE: NONE", as a matter of policy, in describing diamonds that have clearly visible fluorescence.

2) The GIA Gem Trade Laboratory is considered by many as the preeminent gemological laboratory in the world and offers and advertises its services to both the trade and the public at large. As an arm of the non -profit Gemological Institute Of America, its' Diamond Grading Report bears a higher responsibility to the trade and public than other competing commercial enterprises because of good faith reliance on these reports; all levels of the trade pass these reports along as implied or expressed warranties to the buyer.

3) As a small private laboratory, I (as well as most in the trade) see many GIA Gem Trade Laboratory Diamond Grading Reports brought to me by private clients, asking for independent verification whether the diamond in question matches the accompanying report. Most match, but not all do, predominantly when the issue of the diamond's fluorescence is addressed.

4) In analyzing the diamonds fluorescence, I as well as others, use the GIA Gem Instruments (another arm of the Gemological Institute of America) fluorescence viewing cabinet with a 4 inch dual, independently selectable, long wave and short wave excitation source. By any accepted analysis methodology used, "NONE" means "NONE" to those who rely on such reports for financial decisions.

5) In perhaps twenty percent (20%) of the cases where I examine a diamond that is accompanied by a GIA Gem Trade Lab Diamond Grading Report that states "NONE" under the heading "Fluorescence", there appears visible long wave (365nm) fluorescence of varying magnitudes, up to, and including moderate strength. I then have to explain to the client that the diamond appears to be the same diamond as described in the report, with the exception of the issue of fluorescence. This alone, results in additional time spent and costs to my clients.

6) I, and others who take our position and responsibilities seriously, must note these discrepancies in appraisal reports, which further confuses all parties who rely on our appraisal reports for an accurate description of the item. This is of such concern that gemologists and appraisers on the AIS's Appraisers' Information Network (AIN) have discussed the manner and methodology of dealing with this problem for at least the past two years.

7) I have discussed my observations with many in the trade, both publicly and privately, and their observations are consistent with mine, in that this is causing a clear and consistent pattern of apparent deception to the trade and the public at large. It appears that the GIA Gem Trade Laboratory has redefined the meaning of the word "NONE", to mean "less than their 'faint' fluorescent master stone". This redefinition appears nowhere in the report, and the typical buyer of a diamond with GIA paper, is lead to believe that the diamond has no fluorescence.

8) Dealers regularly experience financial loss by bearing the costs of expenses of two way, third party insured, overnight express shipments, when potential buyers discover that the stone sent doesn't match the accompanying report where it describes "Fluorescence". This is a common occurrence with long distance transactions initiated by phone, on the Internet, and in industries when buyers have expressly requested non fluorescent diamonds. Typically, such diamonds are advertised on online as having GIA Gem Trade Laboratory reports that state "Fluorescence: NONE".

9) In addition, if a member of trade or the buying public wishes to have the GIA Gem Trade Laboratory amend the report to reflect the "facts", they are usually required to pay the GIA Gem Trade Laboratory another fee to correct the laboratory's "apparent error".

10) Further, depending on the strength and color of the fluorescence, the diamond's color grade may also be affected by this issue, which can result in even greater financial harm.

11) As an aside, Gemological Institute Of America and GIA Gem Trade Laboratory "standards" regarding fluorescence also can be shown to have been significantly altered over the last decade or so, and manipulated to result in "higher" or better color grades for some diamonds exhibiting blue fluorescence. The public at large, and most in the trade, are unaware of these changing "standards", because the GIA Gem Trade Laboratory publicly states that what they are doing is what they always have done, and there have been no changes in their grading procedures. Most of the people in the trade that I know, take issue with this.

12) To summarize my complaint, which many others in the trade will ultimately back, is that the GIA Gem Trade Laboratory is apparently pursuing a clearly deceptive practice, which ultimately financially harms the trade and the public. It is my strong feeling that the GIA Gem Trade Laboratory and all others in the trade be admonished and enjoined against continuing this clearly deceptive practice, as stated in 16 CFR §23.1
"Deception (general)", "It is unfair or deceptive to misrepresent the type, kind, grade, quality, quantity, metallic content, size, weight, cut, color, character, treatment, substance, durability, serviceability, origin, price, value, preparation, production, manufacture, distribution, or any other material aspect of an industry product." (emphasis added by underlining).

13) I publicly submit this complaint, although I have concern that I may suffer unlawful harassment and severe economic damage as a result of this filing.

14) I am a Graduate Gemologist (GIA) having taken (and contributed to) the educational programs offered by the Gemological Institute Of America, and hold both the people responsible for the teaching, and the educational programs themselves, as offered by the Gemological Institute of America, in high esteem. My technical education includes both Bachelors and Masters of Science degrees from the Massachusetts Institute Of Technology, an education which enables me, I believe, to render objective and qualified technical critiques of the GIA Gem Trade Laboratories practices which I have chosen, out of frustration, to publicly comment on.

Respectfully submitted,

Martin D. Haske GG, NGJA, MS
Adamas Gemological Laboratory
"
P/s
May be GIA changed color system similar.
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
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Messages
14,929
Clarification of what I said:

It is not uncommon for dealers to tell me they see GIA errors.

This is not the same as there are many many errors, it means that a number of dealers and people in the trade have told me they have seen more GIA errors than they normally see.

I will read all the posts and report back :)
 

Richard Sherwood

Ideal_Rock
Joined
Sep 25, 2002
Messages
4,924
You have to be able to interpret Garry's "before wine" and "after wine" posts to avoid going into a tizzy.

Look at what you've gone and started, Garry. Recant and repent, my renegade Australian friend.

One grade, I can see happening once in a while. But "more than one grade"? Come on Garry, admit it. You'd just finished off a bottle of that fine Australian wine when you made that statement, right?
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
14,929
I was tired not drunk you nasty pasty!

Horizon is a system based on Sarin and all the other data that is collected at book in time (quick color, clarity, weight to 3 places and dimensions) that screens the stones to see that they have never been submitted before. That way they always get the same grade and that was designed to stop a possible run of llegal hassles a decade ago.

It is now an enormous data base.

A valuable side benefit is they picked up some GE HPHT treated diamonds that were resubmitted with the 'warning' inscription on the girdle that were polished off by some naugthy person!!

I have invited Marty Haske to let you know what he thinks about this topic.

It is worth noting that very few people in the trade will make a public comment about GIA because they will be consigned to Hell. Some of my personal communications were with a person who knows what they are doing and submit hundreds of stones each week to various labs - mainly GIA and AGS. He could never say these things publicly, and has no vested interest. In fact he is very happy!

I am sure everyone agrees that the GIA SI2 is much softer than it was 10 years ago.
 

Serg

Ideal_Rock
Trade
Joined
Mar 21, 2002
Messages
2,472
----------------
On 1/7/2003 9:47:17 PM

You have to be able to interpret Garry's "before wine" and "after wine" posts to avoid going into a tizzy.

Look at what you've gone and started, Garry. Recant and repent, my renegade Australian friend.

One grade, I can see happening once in a while. But "more than one grade"? Come on Garry, admit it. You'd just finished off a bottle of that fine Australian wine when you made that statement, right?




----------------


Richard,

"more than one grade " is not necessary 2 and more. It has sense
 

optimized

Shiny_Rock
Joined
Dec 28, 2002
Messages
306
This is turning into a pretty interesting thread, eh? I like the lively threads on the forums!

Ready:

I agree that using only a report (GIA or other) to choose a diamond is indeed a bad idea that asks for trouble (it's hard to believe that there actually still are some people who shop by certs alone). Ultimately the diamond itself should be the guide. However, I also think it's important to have some sort of reasonably reliable reference to use for determining some of the characteristics that are otherwise so hard to determine, and that ultimately play such a major role in the pricing of these wildly expensive little chunks of technicolor carbon. I didn't use lab reports as a guide on what to buy, but I most certainly used them to help me determine what they should cost.

My comments really arose mostly from Garry's comment that "GIA have really gone off," and his then going on to mention discrepancies of more than one grade "is not uncommon," which is kind of spooky to think about when the lab has ostensibly been so consistent for so long. His follow-up posts have lent more context to the discussion, and while still not terribly reassuring, helps to put things into perspective.

Serg:

That's a very interesting post about the fluorescence issue! I hadn't heard about that complaint, and agree completely with you that it is good for the health of the industry for these things to be addressed. Actually, just from reading the complaint (with no other background research), I would definitely agree that the term "none" should mean an absolute absence of fluorescence. I can understand why the GIA would classify it as anything "less than their 'faint' fluorescent master stone," but to me that means there should be another tier in between "none" and "faint." I applaud any gemologist willing to go out on a professional limb like that to try to make things better!

Btw Serg, from a purely literal standpoint, Garry's original statement about "more than one grade" by definition does mean "2 and more," as you put it in your last post (unless there's a new VS 1 1/2 I haven't heard of). I'm not arguing, just giving you a hard time. :)

Garry:

I'm glad you clarified your posts, and I for one would welcome any other input you have. I agree that there is an inherent reluctance on the part of many gemologists to criticize the GIA when so much of their business relies on the organization, but I hope any irregularities that are found are exposed so the consumer, and the industry as a whole, is able to recover and move forward with better knowledge.

Richard:

on the GIA site about the procedure they use to certify diamonds, and it goes into a bit of detail about the HORIZON system. The whole article was pretty interesting reading.

-Tim

[/u]
 

Serg

Ideal_Rock
Trade
Joined
Mar 21, 2002
Messages
2,472
Marty Haske Post on DT:

"Another issue regarding fluorescence
35% Of Diamonds Graded Will Now Potentially Get A Better Color Grade By Fiat Of The Gemological Institute Of America

by

Martin D. Haske GG, NGJA, MS

The nonprofit Gemological Institute of America had, for over fifty years, taught tens of thousands of jewelers and gemologists what they, the jewelers and gemologists, thought was the proper way to color grade diamonds. GIA's own historical teaching record summarized below, said in one way or another, that "diamonds should be graded at their poorer color in artificial light devoid of ultraviolet radiation, rather than at their daylight grade".

The GIA diamond color grading system, based on these teachings, was, and still is, the implied "standard" used in the United States and most of the world, and in effect has been codified in 16CFR§23, "Guides for the Jewelry, Precious Metals, and Pewter Industries". 16CFR§ 23.1 Deception (general), states:

"It is unfair or deceptive to misrepresent the type, kind, grade, quality, quantity, metallic content, size, weight, cut, color, character, treatment, substance, durability, serviceability, origin, price, value, preparation, production, manufacture, distribution, or any other material aspect of an industry product."

The framers of these "guides", without explicitly defining such, necessarily expected that there has been, and is, a respectable and defined, repeatable "standard" within the industry, against which one would "grade" factors such as "color", which have such a huge economic impact on the price (or "value") of a consumer item such as a diamond. This implication of repeatability and consistency is paramount to the purpose of the "Guides", that is, to protect the consumer. Unfortunately, that does not appear to be the case.

Documented below is fifty years of GIA teaching the trade a relatively consistent method of observing the "color" in diamonds, that is, until 2002, when abruptly, the illumination source quoted is now daylight fluorescent, with no mention of removing the ultraviolet component from this illumination source. It can be shown scientifically, and is admitted to in the quoted GIA teachings below, that fluorescence, stimulated by ultraviolet, affects perceived color. Any shift to the "white" by adding a blue component to the diamond's color by stimulating fluorescence, can affect perceived color. GIA itself, in its 1997 study in Gems & Gemology, stated parenthetically that 35% of a large random sample of diamonds graded had notable fluorescence. If we are now told by implication, that we have to excite the fluorescence by using unfiltered "daylight fluorescent"2002 illumination instead of "cool white, filtered fluorescent light (UV free)"1990 , then any "standards" which the framers of the "guides" thought to have existed (by implication of 50 years of GIA teachings), have been thrown out the window.

It can be easily demonstrated to most people, that color grade shifts of two to three color grades are not unlikely in stronger fluorescent diamonds, but indeed even a one grade shift in the "advertised" color grade, can make many hundreds, to tens of thousands of dollars difference in the price of a diamond, in every level of the marketplace, especially in the finer clarity stones, VS and better. Going from E to D color, as exemplified in "The Guide" pricing reproduced below, can be a very lucrative shift in the wholesale market. It is any wonder why few in the trade would complain about this switch in color grading technique. However, I wonder what fraction of consumers would complain?


Used With Permission







Appendix A

GIA Diamond Grading Standards
The Historical Perspective

1948 Robert M. Shipley, GIA Course "Gemology, The Science Of Gemstones", Fourth Edition, Section 38 The Diamond Color:

The GIA, after long experimentation with various light sources, developed the Diamondlite, which utilizes a standard Mazda bulb with a filter which removes the preponderance of long wave-lengths of light, noncharacteristic of daylight. The resulting illumination differs from daylight somewhat in that the ultra-violet rays are lacking."

1949 Robert M. Shipley GIA Course "Diamonds", Volume II Section 32 page 1,2

… "Standard conditions of light source and environment, and standardization of methods of color comparison and matching have been established for such commodities such as walnut meats. At the same time, the abuses resulting from the lack of such standardization for diamonds have reached alarming proportions."

…"Daylight, though it is an excellent illumination for distinguishing faint nuances of color when it is good, is not sufficiently constant from day to day, or from one locality to another, to be entirely satisfactory as a standard. Also, the color of fluorescent stones improves in daylight depending upon its content of ultra violet rays."


1972 GIA Course "Diamonds": Assignment 18

…"An instrument for this purpose is the DIAMONDLIGHT(trademark), which utilizes an incandescent bulb with a filter that gives the same balance of wavelengths as north light but with the ultraviolet subtracted. For one who lacks access to a Diamondlite, a fairly effective color-grading light source can be made by using a low-intensity fluorescent fixture with a cool-white tube, filtered through a frosted glass plate, and removed as much as possible from other light sources."

Page 6 "If the stones fluoresce strongly, they will have a different color in daylight than in artificial light."

Page 7 "Also, because of the presence of ultraviolet in sunlight, the color of stones that fluoresce blue improves in daylight."

1978 GIA Course "Diamonds": Assignment 19, page 10

XII. Color Grading Of Fluorescent Diamonds

"Fluorescent diamonds should be graded at their poorer color in artificial light devoid of ultraviolet radiation, rather than at their daylight grade."

1989 GIA Course "Diamond Grading": Assignment 10 Grading Color, page 9 (version E/DY)

"Filtered, cool white balanced fluorescent light is best: unlike sunlight, it is nearly free of ultraviolet"

1990 GIA "Diamond Grading Lab Manual" Page 10 (version H/YA)

"Use cool white, filtered, fluorescent light (UV free) in a darkened room"

1995 GIA Course "Diamond Grading", Assignment 10, page 9 (version E/DY)

"Filtered, cool white balanced fluorescent light is best: unlike sunlight, it is nearly free of ultraviolet" {Note that the grade is grading at the bottom of the DiamondLite, where any UV present in the bulbs used would have the minimum impact on color grade perceived}



1997 Gems & Gemology Winter 1997, "A Contribution To Understanding The Effect Of Blue Fluorescence On The Appearance Of Diamonds", Thomas M. Moses, Ilene M. Reinitz, Mary L. Johnson, John M. King and James E. Shigley

· Page 248: "The data revealed that approximately that approximately 65% of these diamonds {26,010 GIA GTL grading reports} had no reported fluorescence to long wave UV radiation.(Note that a report description of 'none' means that any fluorescence exhibited is weaker than that of the reference stone that marks the none/faint boundary.)" {Comment: This is a convenient, trade beneficial, consumer be damned, redefinition of the word "none".}

· Page 248: "Of the 35% (9,175 diamonds) for which fluorescence was reported, 38% (3,465) were reported as having faint fluorescence and 62% (5,710) had descriptions that ranged from medium to very strong."

· Page 248: Figure 2 shows the Gem Instruments Long Wave / Short Wave 'booth' in use, with the long wave lamp closest to the viewer and furthest from the diamond(s). "At GIA/GTL, the diamond being examined is placed table down and moved between the fluorescence reference stones until the intensity of the fluorescence is stronger than the reference stone on the left and weaker than the reference stone on the right." {One might note that if one were to turn the light around (cord on left) such that the long wave lamp were on the bottom, then you would experience a greater UV luminance on the diamond.}







· Page 251: Table 2 shows five viewing environments:

1. DiamondLite, in a darkened room, Verilux type fluorescent tubes(2)
2. Overhead desk-mounted light in a lighted room, 18" Phillips F15T8/D 15-watt fluorescent tube
3. Overhead desk-mounted light in a darkened room, 18" Phillips F15T8/CW 15-watt fluorescent tube
4. Ceiling mounted room lighting, Phillips FB40CW/6 40-watt fluorescent tubes
5. Window (indirect sunlight), South daylight (1:00-4:00), July, in New York City

{What about UV free cool white, taught for 40 plus years?}
· Page 252: "Because different intensities of ultraviolet radiation in the light sources could affect the diamonds' fluorescence reaction, we used a UVX digital radiometer manufactured by Ultraviolet Products, Inc., to measure the UV content in each of the light sources chosen, The measurements revealed no appreciable differences in long-wave content from one fluorescent light source to the next. According to our measurements, indirect daylight through our windows has about as much UV radiation as the fluorescent light sources." {Comment: evidently the test designers never heard of north daylight, nor of fifty years of teaching, "filtered cool white, devoid of ultraviolet".}

· Page 255: "In other words, there did not appear to be any difference among the light sources we used in their effect on perceived color relative to fluorescence." {Comment: given that each light source above had the same measured UV content, would you expect any difference?}






AND NOW, PRESENTING "THE NEW COLOR GRADING STANDARD"…

2002 GIA Course "Diamonds and Diamond Grading" Page 15

"The most widely available and accepted lighting for color grading diamonds is balanced, daylight equivalent, fluorescent light" {Comment: no mention of UV free, as in the last 50 years.}

2002 Diamond Grading 13, Page 14

{Oh, a strong blue! Lets get a better color grade!}



{Comment: The subtlety here is that you are maximizing the influence of UV on the diamond being graded. Compare this technique to that of the picture shown previously from the 1995 Diamond Grading course Assignment 10.}



--------------------------------------------------------------------------------
http://www.adamasgem.com
http://www.sas2000.com "
 

Kelb_Kabeer

Rough_Rock
Joined
Jan 6, 2003
Messages
2
Thank you all for your comments. I guess I am to understand now that GIA and AGS are the better certs to pay attention to? I want to get a diamond int he next 3-4 months and am considering going through the internet because prices seem to be better for some reason. i can take the stone to a jewler to get it mounted later right? Are there any suggestions of places that people have gone through that are recommended, or does anyone have contact information for a broker that they have ahd a great dealing with? Thank you for any feedback!

Robert
 

optimized

Shiny_Rock
Joined
Dec 28, 2002
Messages
306
In my opinion, yes, the GIA and AGS certs are the ones to look for. That's not to say that other labs don't have good certifications too, but it's generally agreed that these two are the safest. But, as has been mentioned in this thread, don't go solely by the reports since they really don't tell enough about the diamond to determine whether it will be a truly special stone. Many vendors offer additional technical tools to help you decide, but ultimately it should be your eyes that determine what is good! 8)

It's quite simple to have a loose diamond set by a local jeweler. I purchased a diamond online about a month ago (see below for a bit more detail), and had it set by the local jeweler I've dealt with for years. I simply walked in with my diamond, picked out a setting, left the diamond with him, and had a finished ring two days later. It was an absolute breeze. Beware a couple of things though: be sure the jeweler who will set the diamond is trustworthy (I had no concerns since my jeweler and I have done business for many years and have always treated each other fairly), and be sure the dealer isn't one of the many I've heard of (and had secondhand experience with) who might be offended that you didn't buy the diamond from them. These jewelers may try to gouge you, or do something more dishonest.

[/i] page here on pricescope for some useful tips on the pros and cons of buying online.

(who offer far less information about their diamonds). I would shop there again without hesitation.

for a hearty dose of diamond education.

Hope this helps!

-Tim
[/u][/u][/u][/u][/u][/u][/u][/u][/u]
 

Serg

Ideal_Rock
Trade
Joined
Mar 21, 2002
Messages
2,472
The clarity standards cannot cover all border of a clarity zone . It is main reason The basic complexity in an estimation of clarity grade.

I’d like to clarify my statement “more than one grade is not necessary 2 and more”



Let’s consider two examples taking into account that

1) each clarity grade is actually a range of different variations

2) this range is complex multidimensional object, which cannot be represented linearly without breaking of continuity.



First example. Boundary stone. Case when error is absent but the same stone can get into different grades i.e. resulting error is 1 grade.



Let’s take a stone on the border of two grades e.g. SI1/SI2 and clone it. Depending on many factors two identical stones can be graded SI1 as well as SI2. Let’s assume for the sake of simplicity that these events have equal probability for these stones. Then the probability that three independent graders will come to the same conclusions will be 12.5%.



In most cases the opinions will be different and the stone will be sent to a senior expert. He’s more experienced and probability to get into one grade will be higher than 50%. However, there are more than one senior expert hence equal stones will be graded differently if the grading are not done simultaneously.



Second example. An error in grading of 1/3 of a group causes an error of more than one group.



Let’s take two different SI1 diamonds which are on the opposite sides of the SI1 grade canter. One is closer to VS2; the other one to SI2. Let’s assume that the first stone is 1/3 or less from the SI1/VS2 border and the other one is 1/3 or less from SI1/SI2.



Probably everybody will agree that if these stones are graded not at the same time, there is a non-zero probability that these stones will be graded VS2 and SI2. I.e. one grade error for one stone causes 2 grades error for two stones. Now if these stones will come simultaneously to an independent expert, he’ll say that GIA made a mistake for more than 1 grade. However for each stone the error was only one third of a grade.



The real two-grade error: one should consider these two examples simultaneously keeping in mind that clarity grades are multidimensional objects and there can be the points, which are close to more than two boundaries at the same time.



I do not criticize any specific laboratory but point to the objective problems of the correct grading using GIA system.
 

optimized

Shiny_Rock
Joined
Dec 28, 2002
Messages
306
Serg,

That was a sweet explanation you wrote! I really enjoyed the analysis you presented. Very nice.

Unfortunately, I see some problems with your assumptions, and I'd like to address them, and maybe get some more input from you in case I'm missing something.

To begin, the first scenario you propose looks absolutely correct to me, and I would imagine it is the most common form of "inaccurate" grade. I can only imagine how tough it must be for the graders to deal with the boundary stones you mentioned since all of this grading stuff really is so subjective.

The second scenario though seems to take a slight departure from the statement that originally started this discussion, IMO. Basically, my understanding of Garry's original comment, "GIA have really gone off. I have dealers telling me more than 1 clarity grade away is not uncommon," (sorry to keep dragging that original statement back into the conversation, Garry) made it sound like single stones were being inaccurately graded off by more than one clarity grade on the reference GIA scale (e.g. an SI1 diamond is graded as VS1). By introducing the dynamic of two stones at opposite ends of a single grade you are changing the given assumptions of the original statement, and while your example is true within the context of your two stone scenario, it seems to have little to do with Garry's original statement that started this whole drama.

In the two stone scenario you described (with each SI1 stone falling into incorrect grades in opposite directions), indeed the difference between the two stones would be two grades, but each individual stone would still be only one grade off from the "correct" grade, which is the only reasonable comparative reference. Now, if the observer is using one of these misgraded diamonds as a "reference stone," then indeed it would appear that the other diamond was two grades off, but to use a misgraded stone as a reference would in itself be a mistake made by the observer and would not constitute either stone actually being "more than one grade off." Granted, they would be "more than one clarity grade away" from each other, but they each would still only be one grade off from their actual grade, so anybody saying that there was an error of "more than one clarity grade" would be misstating the actual situation since by rights the "true" grade is the only valid reference for comparison.

I tried to think of an analogy to sum up my view here, and this is the best I could come up with at this late hour (it's 6AM here and WAAAY past my bedtime!): If two people were to be asked to paint a line on the ground ten meters long without using any measuring devices, and one painted a line nine meters long while the other painted a line eleven meters long, it would be a mistake to say that either line was "two meters off." Indeed, they would be two meters from each other, but the inviolable truth of the matter is that each line was only one meter off the goal of ten meters. Since the ten meter mark is the point of reference, that is the point that must be measured from. Same thing with the clarity grades. If the SI1 is the actual grade, then each stone must be compared to the correct grade for the "two grades off" statement to have any meaning. That's my take on it, anyway. Am I missing something?

Btw, I only mention all this (in such a verbose manner) because I enjoyed your post so much that I felt compelled to reply with a little bit of analytical-sounding babble of my own. I didn't want to be left out of the lofty stuff. :) I see now that my point was getting rather redundant there toward the end, but I enjoyed writing it so much that I think I'll leave it intact. 8)

-Tim

"Eschew Obfuscation"
 

Richard Sherwood

Ideal_Rock
Joined
Sep 25, 2002
Messages
4,924
I can only remember one time that I've ever seen a GIA graded diamond in which I thought they were more than one grade off on color or clarity. I've probably examined at least 20,000 GIA certified stones over the last two+ decades.

As far as them seeming to have "eased up" on the SI2 grade, if that's the case I'm glad to see it. In my opinion, they have been unrealistically harsh in their grading of this category, grading many SI2 stones as I1's in the past. The Gem Trade Laboratory's grading of SI2's often bore little resemblance to the category which GIA set and taught. I found it irritating as hell that they would teach one standard and then have their lab grade at another standard.
 
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