What separates a VS2 from an SI1 when grading?
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Daisi2112
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Clarity grading factors include size, number, position, relief (visibility) and nature of inclusions. All of them influence the ultimate grade.
Generally, between VS and SI, if the grader views a diamond at 10X and at that magnification the inclusions seem "minor" to him it''s a candidate for VS. If they seem "noticeable" at that mag it''s a candidate for SI. The nature of those inclusions does come into play too; small crystals, feathers and clouds are allowed in VS. When they are not so small it can drop the diamond to SI.
Generally, between VS and SI, if the grader views a diamond at 10X and at that magnification the inclusions seem "minor" to him it''s a candidate for VS. If they seem "noticeable" at that mag it''s a candidate for SI. The nature of those inclusions does come into play too; small crystals, feathers and clouds are allowed in VS. When they are not so small it can drop the diamond to SI.
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When GIA/AGS strictness is enforced Daisi''s comment will be true in the vast majority of cases. There are some situations where it may be possible to have an eye-visible inclusion in VS. Grading is done at 10X, regardless of diamond size and shape. An example given in GIA''s coursework is a large emerald cut that has a single eye-visible included crystal under the corner of the table but still falls into the VS range.
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Another factor is the size of the diamond.
i.e. take a photo of an included diamond and label the same photo 0.30, 0.70 and 10ct and it could get different grades simply based on its overall size because in the mid to lower grades the inclusions are based on how much of the diamond they take up.
In IF - VVS grades the size of the inclusion is the only factor.
An SI2 inclusion in terms of the relative size of the stone in a 0.30ct diamond could be an SI1 inclusion in a .75ct diamond, and in a 10ct diamond it could be a VS2.
i.e. take a photo of an included diamond and label the same photo 0.30, 0.70 and 10ct and it could get different grades simply based on its overall size because in the mid to lower grades the inclusions are based on how much of the diamond they take up.
In IF - VVS grades the size of the inclusion is the only factor.
elle_chris
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Years ago, when I didn''t know more about larger diamond grading, I had an uncerted 4.00 carat marquise which looked to me to be I1 clarity. It needed a GIA report and when it came back it was graded SI1...... Those kind of lessons are not the ones GIA teaches its students in the correspondence courses. The lab grades diamonds on a sliding scale which is weight dependent. When one is training with GIA the grading is all geared to proper assessment of rather small diamonds. Little mention used to be made of how the lab grades larger diamonds. Experience teaches what is left out of the courses.
If you have ten diamonds graded SI1 and ten diamonds graded VS2 of similar weight range and show them to several trained and experienced graders you will get quite a bit of grading that has SI1''s becoming VS2''s and the reverse. You''ll likely get a few SI2 and VS1 grades offered , as well. Some mid-grade stones will not be switched in grading by skilled graders, but borderline cases will crosss into the other grade quite often. It is not a problem for doing business, but seems to create fear among consumers. Prices tend to adjust according to the actual level of quality in each diamond. A low SI1 is worth a bit less than a high SI1, etc, etc. Prices are far more able to slide and adjust properly than the few rigid grades we accept to use to describe clarity. In the end, it all makes reasonable sense.
If you have ten diamonds graded SI1 and ten diamonds graded VS2 of similar weight range and show them to several trained and experienced graders you will get quite a bit of grading that has SI1''s becoming VS2''s and the reverse. You''ll likely get a few SI2 and VS1 grades offered , as well. Some mid-grade stones will not be switched in grading by skilled graders, but borderline cases will crosss into the other grade quite often. It is not a problem for doing business, but seems to create fear among consumers. Prices tend to adjust according to the actual level of quality in each diamond. A low SI1 is worth a bit less than a high SI1, etc, etc. Prices are far more able to slide and adjust properly than the few rigid grades we accept to use to describe clarity. In the end, it all makes reasonable sense.
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Absolutely correct - but not as frightening as it might seem. In our process, for example, we must be able to predict yield and grading while the diamond lies in the rough crystal, otherwise we could never bid accurately enough to win parcels or be profitable. Through the process of mapping, design and polish we will again pre-grade every diamond least three times before it leaves our facility for the lab. We are more familiar with each diamond we craft than any grader ever will be, so with the situation described above one would think we'd be raging against the machine (!), working on razor-thin margins which depend on such predictions (VS or SI). Fortunately the fact that the final grade is a consensus of more than one grader mitigates some of the inconsistency.
Really Dave?
The sliding scale you describe, and grades from the reputable labs on the whole, do make sense on the whole - for what the system is currently.
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Hi John...Date: 2/23/2009 1:45:24 PM
Author: John Pollard
Absolutely correct - but not as frightening as it might seem. In our process, for example, we must be able to predict yield and grading while the diamond lies in the rough crystal, otherwise we could never bid accurately enough to win parcels or be profitable. Through the process of mapping, design and polish we will again pre-grade every diamond least three times before it leaves our facility for the lab. We are more familiar with each diamond we craft than any grader ever will be, so with the situation described above one would think we''d be raging against the machine (!), working on razor-thin margins which depend on such predictions (VS or SI). Fortunately the fact that the final grade is a consensus of more than one grader mitigates some of the inconsistency.
Really Dave?Not-knowing whether SI1-I1 (and the rare VS) are going to be eye-clean or not without elaborate ''eye-clean'' discussions and review of each individual diamond drives me crazy...but I''m probably on a different tangent than you intended.
The sliding scale you describe, and grades from the reputable labs on the whole, do make sense on the whole - for what the system is currently.
Any ideas taking subjectivity out of the equation?
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No doubt many of us have had that conversation many times, eh DG? It would be nice, but they're snowflakes. I would like to see a grading border that means (standardized) eye-clean on one side and not eye-clean on the other.
Mechanical: You think we'll crack colorimetry - face-up - before we crack clarity?
strmrdr
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I suppose that it makes "reasonable sense" to me, not to everyone. Since I combine lab grading with dollar valuation processes, the end result of "value" does make sense even when the grading itself seems a bit on the erratic, subjective level, the value can be much finer tuned to give what I see as reasonably sensible outcomes.
From an outsider''s perspecitve, it does sound rather scary and error prone. We have learned to live with it and consumers should not be fearful of diamond grading or getting good value for their money when working with properly vetted and recommended vendors. For the impulsive or the naive, buying nearly anything is dangerous. Diamonds can be much more carefully documented and proven than many other equally expensive consumer items.
From an outsider''s perspecitve, it does sound rather scary and error prone. We have learned to live with it and consumers should not be fearful of diamond grading or getting good value for their money when working with properly vetted and recommended vendors. For the impulsive or the naive, buying nearly anything is dangerous. Diamonds can be much more carefully documented and proven than many other equally expensive consumer items.
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Part of the reason that we don''t yet have objective standards for color or clarity is because compliance is voluntary currently. There are diamonds floating around with no lab reports, with excellent lab reports and with highly problematic lab reports. Expert dealers know how to handle all of this by looking at the diamond and adjusting the price to meet the value of the diamond regardless of the report. I''ll admit that a fortunate, high grade, adds some value where it probably is not well justified in that that dishonesty still pays off a bit occasionally. Keeping the non-experts a little in the dark adds to the mystery of diamonds and prevents everyone from knowing all the facts. This suits diamond dealers because they want to be in charge of their product and market.
The biggest diamond dealers are the largest users of GIA reports. They prefer to keep doing business with the devil they know than to give up the "subjective grading" excuse and pay for objective color and clarity reports which they cannot wiggle with. The major labs hesitate to anger their main clients with some new twist on the old deal. No doubt. major labs have looked into technically objective grading and while they could do it, they have few clients, if any, who would prefer it.
Many changes in our technological society have come from small, start up firms who brought a giant step forward into the market that would have been frozen in place by the major firms for years had they not come along and offered something new and better. These start ups often get bought out by the big businesses, but by then, the genie is out of the bottle. I think we''ll see objective grading come into its own in the next few years, but it will come from outside and not from GIA or AGSL although they could do it if they and their customers wanted it. We will have consumers bringing pressure to bear on the big guys as they discover and demand more accurate services which get into the market from technologically astute, new firms. In spite of our current economy, it is an exciting time to be involved in diamonds.
The biggest diamond dealers are the largest users of GIA reports. They prefer to keep doing business with the devil they know than to give up the "subjective grading" excuse and pay for objective color and clarity reports which they cannot wiggle with. The major labs hesitate to anger their main clients with some new twist on the old deal. No doubt. major labs have looked into technically objective grading and while they could do it, they have few clients, if any, who would prefer it.
Many changes in our technological society have come from small, start up firms who brought a giant step forward into the market that would have been frozen in place by the major firms for years had they not come along and offered something new and better. These start ups often get bought out by the big businesses, but by then, the genie is out of the bottle. I think we''ll see objective grading come into its own in the next few years, but it will come from outside and not from GIA or AGSL although they could do it if they and their customers wanted it. We will have consumers bringing pressure to bear on the big guys as they discover and demand more accurate services which get into the market from technologically astute, new firms. In spite of our current economy, it is an exciting time to be involved in diamonds.
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Yes, here is an idea, let it be a personal choice of the consumer or the retailer.Date: 2/23/2009 2:08:29 PM
Author: DiaGem
Hi John...Date: 2/23/2009 1:45:24 PM
Author: John Pollard
Absolutely correct - but not as frightening as it might seem. In our process, for example, we must be able to predict yield and grading while the diamond lies in the rough crystal, otherwise we could never bid accurately enough to win parcels or be profitable. Through the process of mapping, design and polish we will again pre-grade every diamond least three times before it leaves our facility for the lab. We are more familiar with each diamond we craft than any grader ever will be, so with the situation described above one would think we''d be raging against the machine (!), working on razor-thin margins which depend on such predictions (VS or SI). Fortunately the fact that the final grade is a consensus of more than one grader mitigates some of the inconsistency.
Really Dave?Not-knowing whether SI1-I1 (and the rare VS) are going to be eye-clean or not without elaborate ''eye-clean'' discussions and review of each individual diamond drives me crazy...but I''m probably on a different tangent than you intended.
The sliding scale you describe, and grades from the reputable labs on the whole, do make sense on the whole - for what the system is currently.
Any ideas taking subjectivity out of the equation?
Show alll the info about each diamond so people can choose for them selves.
Like this http://diamondscope.pricescope.com/
see the first video in the top left
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Dave..., I know loads of Diamond dealers who would want/prefer a more consistent technique of grading Diamonds..., it would make their life much easier..., (even if most of them dont know itDate: 2/23/2009 3:31:41 PM
Author: oldminer
Part of the reason that we don''t yet have objective standards for color or clarity is because compliance is voluntary currently. There are diamonds floating around with no lab reports, with excellent lab reports and with highly problematic lab reports. Expert dealers know how to handle all of this by looking at the diamond and adjusting the price to meet the value of the diamond regardless of the report. I''ll admit that a fortunate, high grade, adds some value where it probably is not well justified in that that dishonesty still pays off a bit occasionally. Keeping the non-experts a little in the dark adds to the mystery of diamonds and prevents everyone from knowing all the facts. This suits diamond dealers because they want to be in charge of their product and market.
Dont know Dave..., seems to me as Diamond Dealers are far from being in charge of their products..., (uhhhm..., GIA et-al, Rapaport et-al, Rough producers and even retailers....)
The biggest diamond dealers are the largest users of GIA reports. They prefer to keep doing business with the devil they know than to give up the ''subjective grading'' excuse and pay for objective color and clarity reports which they cannot wiggle with. The major labs hesitate to anger their main clients with some new twist on the old deal. No doubt. major labs have looked into technically objective grading and while they could do it, they have few clients, if any, who would prefer it.
Many changes in our technological society have come from small, start up firms who brought a giant step forward into the market that would have been frozen in place by the major firms for years had they not come along and offered something new and better. These start ups often get bought out by the big businesses, but by then, the genie is out of the bottle. I think we''ll see objective grading come into its own in the next few years, but it will come from outside and not from GIA or AGSL although they could do it if they and their customers wanted it. We will have consumers bringing pressure to bear on the big guys as they discover and demand more accurate services which get into the market from technologically astute, new firms. In spite of our current economy, it is an exciting time to be involved in diamonds.
Dealers depend[ed] on Rap (for pricing their wares)..., they also depend on GIA et-al (for pricing their wares).
And these days of turmoil are evidence that Diamond dealers lost their sense of (value) direction...
Just one question..., how can/could they do it???
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Problem with transparency (I agree)??? Whats the connection with yes eyeclean****no-eyeclean?Date: 2/23/2009 3:51:08 PM
Author: Garry H (Cut Nut)
Yes, here is an idea, let it be a personal choice of the consumer or the retailer.Date: 2/23/2009 2:08:29 PM
Author: DiaGem
Hi John...Date: 2/23/2009 1:45:24 PM
Author: John Pollard
Absolutely correct - but not as frightening as it might seem. In our process, for example, we must be able to predict yield and grading while the diamond lies in the rough crystal, otherwise we could never bid accurately enough to win parcels or be profitable. Through the process of mapping, design and polish we will again pre-grade every diamond least three times before it leaves our facility for the lab. We are more familiar with each diamond we craft than any grader ever will be, so with the situation described above one would think we''d be raging against the machine (!), working on razor-thin margins which depend on such predictions (VS or SI). Fortunately the fact that the final grade is a consensus of more than one grader mitigates some of the inconsistency.
Really Dave?Not-knowing whether SI1-I1 (and the rare VS) are going to be eye-clean or not without elaborate ''eye-clean'' discussions and review of each individual diamond drives me crazy...but I''m probably on a different tangent than you intended.
The sliding scale you describe, and grades from the reputable labs on the whole, do make sense on the whole - for what the system is currently.
Any ideas taking subjectivity out of the equation?
Show alll the info about each diamond so people can choose for them selves.
Like this http://diamondscope.pricescope.com/
see the first video in the top left
Can subjectivity be taken out of the grading? Is their news I am not aware of? I would be glad to learn...
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DiaGem; You seem ready to try it, but I''m afraid most dealers would be much more skeptical. The first stone which grades E that previously was graded D color would be a huge turn off. Dealers are used to appealing low grades, but often toss out reports with lower than expected grades. If all labs graded the same, there would be a lot of pain until folks accomodated themselves to the new reality. How would GIA like it if their grading was no better than my personal machine grading? Do you think they would want to adopt a fair and level playing field for their competition? No dealer wants to re-grade their current huge inventories. Just imagine the added, unwanted cost to do it. There is a lot of resistance readily apparent.
I know people have lost their way, but it is temporary. Time will get us all back on an understandable path although there may be fewer of us involved a year or two from now. Innovators will have a good opportunity to bring new technology with money saving elements into the mix as old line dealers increasingly struggle with today''s new reality. I see a lot of distress right now, but with it comes great opportunity. I hope we wiill see technology advance in our field at a more rapid pace. Machine color grading works and it is more repeatable than human color grading, BUT it is not identical to human grading in every respect. It may be better, but not identical. There are faults with the way things are that can''t be worked around without fudging the results or dummying down the process.
I know people have lost their way, but it is temporary. Time will get us all back on an understandable path although there may be fewer of us involved a year or two from now. Innovators will have a good opportunity to bring new technology with money saving elements into the mix as old line dealers increasingly struggle with today''s new reality. I see a lot of distress right now, but with it comes great opportunity. I hope we wiill see technology advance in our field at a more rapid pace. Machine color grading works and it is more repeatable than human color grading, BUT it is not identical to human grading in every respect. It may be better, but not identical. There are faults with the way things are that can''t be worked around without fudging the results or dummying down the process.
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From my experience..., color machines are doing a "just ok" job in the "H" plus category..., but are terrible in the lower colors. And I am not talking about a specific color grade but rather consistency of repeatability!
Now..., any news on machine clarity grading? You did say they could if....
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Did you watch the video DG?
Have you seen the demo included in the latest download of DiamCalc?
http://www.octonus.com/oct/download/diam_demo_down.phtml
This technology currently grades higher clarity diamonds using HRD''s attempted system from a decade or more ago. It is micron and shade based and is used in Helium, Pacor and MBox rough scanning technology.
The viewing format for consumers and retailers will be a version of Gem Adviser. OctoNus are actively working on this project now.
Of course it will initially be most interesting for scanner users as they are doing the work to map the inclusions as part of the rough allocation process, and have already captured the included inclusions before they cut the stone.
There will however also be Helium Polished scanner technology to confirm the inclusions in the polished, as well as map the stones that were not allocated from OctoNus scanners.
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