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DIAMOND GRADING- Is it a science?

Discussion in 'FAQ' started by Richard Sherwood, Nov 12, 2003.

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  1. Richard Sherwood
    Ideal_Rock

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    by Richard Sherwood » Nov 12, 2003
     
  2. Richard Sherwood
    Ideal_Rock

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    by Richard Sherwood » Nov 12, 2003
    -----------
    Individuals grading with an inherent bias (they’re selling the stone,
    or have a vested interest in its sale.
    -----------

    You know, in re-reading my post this statement doesn't ring correct to me. There are plenty of ethical dealers who grade their stones strictly and wouldn't think of letting bias creep into it.

    This statement would apply to the minority of dealers who let the fact that they're selling the stone influence their grading. The majority of dealers are straight arrows when it comes to this matter.
     
  3. canadiangrrl
    Brilliant_Rock

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    by canadiangrrl » Nov 12, 2003
    Thanks for the information. On a related note, there are two things I would like to know:

    1) I have a diamond that was willed to me by my grandmother. Years ago, I had it professionally appraised in Toronto, and the appraiser used (I swear this is how I remember it) some little hand-held tool to that appeared measure the diamond. Any idea what I was seeing? Does such a little gadget actually exist? If so, was it replaced with the advent of the Sarin & OGI Megascope?

    2) The terms "high F" or "low G" sometimes get referred to around here. Is it really possible to spot variances within a single colour grade? If so, is my stone a "high F", or a "low F" ? [​IMG]
     
  4. strmrdr
    Super_Ideal_Rock

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    by strmrdr » Nov 12, 2003
    What is your opinion of the whole si3 grade situation?
     
  5. valeria101
    Super_Ideal_Rock

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    by valeria101 » Nov 13, 2003

    So ethical restraints bend the short-term interest in front of the long-term desire to build reputation and career...

    How about the other class of crook (joke): "Individuals grading without the supporting equipment (microscope, master stones, etc" dealers buy diamonds un-graded at some point. Are those grading tools more useful when transferring diamond from knowledgeable to not knowledgeable party (such as retailer and consumer), rather then when passing diamond between too diamond professionals? Just my (well intended) hunch...
     
  6. Garry H (Cut Nut)
    Super_Ideal_Rock
    Trade

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    by Garry H (Cut Nut) » Nov 13, 2003
    The ethics issue is most intersting Rich (your whole thesis is well written by the way).

    I often look at what my staff grade a stone as and think "wow these bastards are being pedantic, this SI1 is easily a VS2" - but then I see how much professional respect there is within my business. We have never ever been accused of misgrading a stone by anyone oustide our doors in 28 years of business. So the only way to ensure that reputation is for me to shut my trap and never ever ask anyone to upgrade a grading call!

    An intersting aside - we sent a stone to a local lab and it came back G I1 - we bought the stone conditional on G SI2. The supplier was upset and sent it at his cost to GIA. It came back G SI1. We have the stone on sale at G SI2 because we still believe that is what it is.

    Are we always right? Thaat is the whole point - grading is subjective. Some people grade easy to make a quick sale and others grade hard to protect a hard earned reputation.
     
  7. Rank Amateur
    Brilliant_Rock

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    by Rank Amateur » Nov 13, 2003
    The bias is evident when the French judge holds up the 5.5 card for the American diver when everyone else has 9.0s.
     
  8. winyan
    Brilliant_Rock

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    by winyan » Nov 13, 2003
    My head has gone round and round on the Si3 thing.

    I'm the last person to yell expert, I just like sparklies, however, I do have a peach marquise, a little over a half carat (.67) that was graded a Si3.

    Since colored diamonds are cut for intensity of color, and not clarity, the Si3 rating bothers me not at all.

    It's simply a pretty little stone.

    win
     
  9. Richard Sherwood
    Ideal_Rock

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    by Richard Sherwood » Nov 13, 2003
    -----------
    1) I have a diamond that was willed to me by my grandmother. Years ago, I had it professionally
    appraised in Toronto, and the appraiser used (I swear this is how I remember it) some little hand-
    held tool to that appeared measure the diamond. Any idea what I was seeing? Does such a little
    gadget actually exist? If so, was it replaced with the advent of the Sarin & OGI Megascope?
    -----------

    The handheld tool was probably a Leveridge millimeter gauge, which is universally used by jewelers to measure diamonds. It gives basic dimensions, but doesn't give the detailed information that a Sarin or OGI machine does.

    -----------
    2) The terms "high F" or "low G" sometimes get referred to around here. Is it really possible to
    spot variances within a single colour grade? If so, is my stone a "high F", or a "low F"?
    -----------

    Dealers argue about this all the time. Some maintain that being able to divide a single color grade into a "low, dead-on and high" grade is nonsense, while other's insist that they can often see the difference.

    The argument for being able to see this difference was strengthened when the Austron colorimeter came out on the market. It has a linear scale with five blocks designated for each color. The machine then "blacks out" three of the five squares. Depending on where these blacked out squares fall, dealers refer to the designation as a "high" grade, "dead-on" grade, or "low" grade.

    I think it is possible to discern in some cases whether a stone is a "high" or "low" grade. It doesn't usually make much difference in the marketplace, but it's kinda fun to kick around.

    Canadiangirl, your stone for example (and I told your finacee this upon giving him the color grade) is what I would call a "high" F, very close to straying into "E" territory, but not quite.
     
  10. Richard Sherwood
    Ideal_Rock

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    by Richard Sherwood » Nov 13, 2003
    -----------
    What is your opinion of the whole si3 grade situation?
    -----------

    I personally feel there are some cases in which the SI3 grade is warranted.

    The Rap Sheet, which is a Trade Publication, honors the SI3 grade given out by EGL, the European Gemological Laboratory. The grade has also been endorsed in a year 2000 meeting of the World Diamond Congress, and accepted by the World Federation of Diamond Bourses.

    This grade has unofficially been acknowledged among dealer for decades, with many dealers paying more money for an "SI3" than they would for a mainline "I1".

    By my thinking as an appraiser, if there is a quality designation which has an affect on value, then it is my obligation to use it if warranted.
     
  11. Richard Sherwood
    Ideal_Rock

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    by Richard Sherwood » Nov 13, 2003
    -----------
    Are those grading tools more useful when transferring diamond from knowledgeable to not
    knowledgeable party (such as retailer and consumer), rather then when passing diamond between too
    diamond professionals? Just my (well intended) hunch...
    -----------

    Yes, I would say that is an accurate assessment, Valeria. Many professional dealers are confident enough in their own grading abilites to buy diamonds without needing a cert to refer to. There are dealers that prefer buying certed stones only however. Others might like a cert on a particularly valuable stone, or one which seems a borderline grade.

    At the end transaction though (dealer to consumer), there is no better selling tool than a cert. It puts the consumer's mind to rest regarding the diamond's quality.
     
  12. canadiangrrl
    Brilliant_Rock

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    by canadiangrrl » Nov 13, 2003
    Thanks Rich, your explanation on colour makes perfect sense. [​IMG]

    Like many of the consumers who post here, I received a copy of Fred Cuellar's book in the mail. He talks about setting price points based on the Colorimeter rating, e.g. an F1 (high F) would be worth more than an F5 (low F.) I can't even begin to imagine the cluster this would cause if the labs began to officially recognize colour grade typing. [​IMG]

    And just as a random aside, I have duly noted that not only does Garry look fantastic in a ski suit, but he also successfully used "pedantic" in a sentence. *drool* [​IMG]

    Edited to add that Mr. Canadiangrrl retained only one thing from your conversation - "It's beautiful." He remembers you saying a whole lot more but was so immensely relieved at that point that everything else went right out the window. [​IMG]
     
  13. strmrdr
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    by strmrdr » Nov 13, 2003

    How would most of the diamonds you have seen rated si3 be rated if it didnt exist?
    Would they be sold as low end si2 or as i1?
    If they would be rated as i1 isnt this just putting a spin on a poor stone in an attempt to get more money for it?
    Iv read elsewhere that the si3 rating is just another way to rip off the unknowing and because I respect your opinion more than some random website I want to make sure I understand your thoughts on it.
     
  14. Garry H (Cut Nut)
    Super_Ideal_Rock
    Trade

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    by Garry H (Cut Nut) » Nov 13, 2003
    THEY ARE BETTER STORES I1'S OR LOW RETAIL MARKET SI'S
     
  15. Richard Sherwood
    Ideal_Rock

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    by Richard Sherwood » Nov 14, 2003
    -----------
    How would most of the diamonds you have seen rated si3 be rated if it
    didnt exist?
    -----------

    That's the crux of the problem. Most these stones were graded as I1's by GIA for decades. But the price disparity between an I1 and an SI2 is huge, while the visual difference between these SI3 category stones and SI2 is often minimal.

    So a market driven category of stones gained value among dealers, because they could recognize that this category of stones would bring more money from both dealers and the public than a mainstream I1.

    Dealers were willing to pay more for this category of stone, and were able to sell it for more to the public.

    So a market arose which GIA had no category for, and indeed refused to consider creating one, even though the entire diamond industry admitted that it already existed. Kind of a case of the tail trying to wag the dog, with the entire diamond industry being the dog and GIA being the tail.

    Finally Tom Tashey at EGL along with the feisty Martin Rapaport recognized reality and began acknowledging this grade, with EGL grading it and Rapaport reporting it in his influential pricing sheet.

    Many hailed their courage, while others cursed them. By my mind, they were just grading and reporting an already established reality.

    -----------
    Would they be sold as low end si2 or as i1?
    -----------

    They're usually sold at the midway point between SI2 and I1 pricing. Take the 1 carat G color category for example.

    G/SI2.....4900 per carat
    G/I1......3500 per carat

    You're talking a 40% price drop from SI2 to I1. If the stone is a mainline I1, then you don't mind so much. But when it is a gorgeous, very nearly eyeclean stone which it is almost a shame that GIA graded it an SI2, then it's another story. Does that stone really deserve to bring 40% less?

    Many dealers didn't think so, and began refusing to sell these stones among themselves for 40% less. They would split the difference and say "It's an SI3!", before the grade even officially existed. The buying dealers would begrudgingly admit that the stone was more visually beautiful and a mainline I1, and would step up to the pump and pay the price. The public in turn did the same, turning an unacknowledged grade into a market reality. (That reality is now reflected in Rapaport's reporting of a 1ct G/SI3 at 4200 per carat.)

    Now the SI3 grade is officially acknowledged, not only by EGL and Martin Rapaport, but also by the World Diamond Congress and the World Federation of Diamond Bourses.

    This problem became very focused for me when I was once appraising a 5 carat F color round brilliant cut for a client. The stone was a top, top I1, borderline SI2. I recognized it immediately as a stone which would trade among dealers as an "SI3". The price differential between it as an SI3 and an I1 was 25%, which amounted to almost $9,000.

    As an appraiser, my duty is to report any factors which affect the value of the gemstone. This was truly a case where it was a crime to report the grade as an I1, or exagerrate the grade to report it as an SI2. I therefore grading it an SI3, carefully explaing the grade to the client.

    I've been using the SI3 grade ever since. I try to use it sparingly, only in cases where it is glaringly called for.

    -----------
    If they would be rated as i1 isnt this just putting a spin on a poor
    stone in an attempt to get more money for it?
    -----------

    In my opinion it is reporting a market reality, rather than trying to get more money for something than it inherently deserves. One thing I can guarantee you: diamond dealers will not pay more for something than it's worth. If a stone is an I1 and doesn't warrant an SI3, there is no way in hell you will be able to pull the extra premium out of a dealer. If there wasn't a market reality behind this grade the whole category would collapse.

    -----------
    Iv read elsewhere that the si3 rating is just another way to rip off
    the unknowing and because I respect your opinion more than some random
    website I want to make sure I understand your thoughts on it.
    -----------

    I look at it this way. Diamond dealers are probably the largest single knowledgable consumer group of diamonds worldwide. They are extremely savvy diamond connoiseurs, far from "unknowing". If they are willing to pay this premium themselves, I certainly wouldn't call it a rip off for them to charge that same premium to the public.
     
  16. strmrdr
    Super_Ideal_Rock

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    by strmrdr » Nov 14, 2003
    Thanks Rich
    That clears it up for me.
     
  17. mhtv
    Rough_Rock

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    by mhtv » Feb 15, 2004
    each clarity grade category has a high end and a low end. as the clarity catgory gets lower, the range within that grade gets larger. for instance, the difference between the high and low ends of the vs1 grade is not as distinct as that difference between the high and low ends of the SI1 grade. with the I1 grade as used by the GIA, the difference between the high and low ends of that grade are so great that it is not logical to use the same grade term to describe them. the mid to low GIA I1's are so distinctly different from the higher end of the GIA I1 grade, that using one grade term to describe them is misleading, and not sufficiently meaningful.

    therefore,the trade has always used the SI3 term, or some similar means to make the distinction that the GIA fails to make.

    as for the idea of it being a "ripoff", that is incorrect for the reasons provided above, and it also involves a misconception of the nature of diamond grading. putting the label "SI3" on a diamond does not change the diamonds appearance...its quality. the diamond remains what it is no matter what you call it. and especially in the SI2 and lower grades, the actual appearance will have a very determining factor on desirability independant of the grading terms assigned.

    as for what most SI3's would grade by the GIA, this also involves a misconceptgion of lab grading. even the GIA grades inconsistently, and what today is a GIA SI2, might tomorrow be a GIA SI1, or GIA I1. but even if most SI3's are graded I1 by the GIA, this does not negate the fact that they are very different than mid to lower GIA I1's and so the SI3 designation is completely appropriate and meaningful.
     
  18. Nicrez
    Ideal_Rock

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    by Nicrez » Feb 17, 2004
    How do you guys feel about the segmented S and I categories that some Indian gemologists use? Considering the stones in the Indian cutter's wheel are generally smaller and more colored, they do see a heck of a lot of stones within those "new ranges". Do you ever think the ranges of SI and I's will be regulated into subcategories of 3's and so forth?
     
  19. Richard Sherwood
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    by Richard Sherwood » Feb 17, 2004
    -----------
    How do you guys feel about the segmented S and I categories that some
    Indian gemologists use?
    -----------

    Hi Nicrez. This is interesting. Would you explain it a little more fully?

    Do you mean that some Indian gemologists are using SI and I categories differently than Western gemologists?

    I do a fair amount of grading for an Indian diamond dealer here in Sarasota who gets his diamonds from his cousins in India. The one thing I've noted is that they tend to "high grade" the stones. A lot of what they grade VS I grade as SI, and a lot of what they grade SI I grade as I1. These aren't lab grades, but dealer grades. (I could say the same for a lot of NY dealer grading as well, for that matter.)

    Are you referring to Indian lab graded stones?
     
  20. Richard Sherwood
    Ideal_Rock

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    by Richard Sherwood » Feb 17, 2004
    -----------
    with the I1 grade as used by the GIA, the difference between the high
    and low ends of that grade are so great that it is not logical to use
    the same grade term to describe them. the mid to low GIA I1's are so
    distinctly different from the higher end of the GIA I1 grade, that
    using one grade term to describe them is misleading, and not
    sufficiently meaningful.

    therefore,the trade has always used the SI3 term, or some similar
    means to make the distinction that the GIA fails to make.
    -----------

    Exactly, MHTV. It's a mystery to me why GIA will not acknowledge this market reality in their grading. They are so stubborn when it comes to some things.

    Take for example their stubborness in not reporting the crown/pavilion height/angles. An absolutely essential ingredient in determing cut quality, yet they refuse to divulge this information, even though they make an internal note of it when examining diamonds.
     
  21. andrei
    Rough_Rock

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    by andrei » Feb 17, 2004
    Hi I am new to this forum but have found it perhaps the most useful in educating myself as a consumer. Could you please help me understand the value of a GIA cert over an AGS cert? It appears that GIA-certed stones are a good-deal more expensive. I have heard some of the most reputable stores in my neck of the woods say don't get anything other than a GIA. Other stores of similar reputation say that it doesn't matter and that you are paying more for the GIA name when AGS will give you the same quality certification. Any wisdom?

    Thanks! Andrei
     
  22. pqcollectibles
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    by pqcollectibles » Feb 17, 2004
    I personally like AGS Certs. All the info a customer needs to use the HCA is right on the Cert. You can plug the HCA and get an idea if the diamond is well cut, what to expect in perfomance, and buying recommendations. With a GIA Cert, you have to get Sarin/OGI info from the Vendor. Sometimes that info is readily available, and sometimes it's not. My Sarin corresponded very well to the AGS Cert. Minor variation in the depth % (0.1%) and the table (0.2%), but the angles were right on.

    Both are quality labs, but IMHO, the information available on the AGS Certs makes the buying decision much easier. [​IMG]
     
  23. Richard Sherwood
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    by Richard Sherwood » Feb 18, 2004
    The AGS lab is regarded among dealers as credible as the GIA lab, if not more so. A GIA certed stone and AGS certed stone (of equivalent carat, color, clarity & cut) should command about the same price. The GIA stone shouldn't be more than the AGS.

    I personally prefer the AGS cert, for the reasons PQ mentioned above. It annoys me that GIA holds back crucial information regarding cut on their reports.
     
  24. caseyt
    Rough_Rock

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    by caseyt » Sep 30, 2004
    I have the opportunity to purchase a 1.07 Princess cut. Can you please tell me what you think on the below specs.......what would be a good price? I am a first time buyer and am scared to death.........


    1.07
    G
    SI1
    5.66 - 5.65 X 3.96m
    Depth 70.1
    Table wideth 75
    Crown Height is 9
    Pav Depth 59
    Polish VG
    Sym VG
     
  25. katbadness
    Shiny_Rock

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    by katbadness » Sep 30, 2004
    CaseyT,

    Welcome to PS.

    Why don't you post your question on the RockyTalky forum. There are quite a number of people there who will be more than willing to help you who know princess cuts quite well.
     
  26. caseyt
    Rough_Rock

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    by caseyt » Sep 30, 2004
    thanks
     
  27. Nicrez
    Ideal_Rock

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    by Nicrez » Nov 22, 2004
    Has anyone read GIA''s Cut anlysis in Gems & Gemology....what do you think of it?
     
  28. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Nov 22, 2004
    It is like social science.
    I will finish my review and post it in the journal section soon.
     
  29. Nicrez
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    by Nicrez » Nov 23, 2004
    I am currently reading it, and very interested on your take Garry!!! Why do I feel like my eyes are going to pop out of my head, and does anyone else feel this article is a bit self promoting, I almost feel like waiving a GIA flag.... Wait, I didn''t say that... [​IMG]
     
  30. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Nov 24, 2004
    It makes me think that 12 authors might be a little too much for one competent Editor to handle.

    It reminds me a little of what the Economist magazine said about the choice you guys had in your election:
    The incompetent, or the incoherent
     
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