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»  » New GIA cut-grading-system launch Jan 2006
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| Pages: 1 of 2: [1] 2 > |
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New GIA cut-grading-system launch Jan 2006 |
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| P: 8/2/2005 11:43:17 AM | |
Paul-Antwerp Ideal Rock Total Posts: 1,911 Last Post: 11/24/2009 Member Since: 9/3/2002 |
GIA has officially announced that they will start their new cut-grade from Jan 1st, 2006. Information is bundled in this website: link If you use the Facetware-button on this site, you can play around with proportions yourself. Enjoy,
Paul Slegers Infinity Diamonds www.CraftedByInfinity.com |
| Posted: 8/2/2005 11:43:17 AM | |
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There are 33 replies to this message. There are 30 replies on this page. |
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| P: 8/2/2005 2:16:17 PM | |
belle Ideal Rock Total Posts: 10,287 Last Post: 4/3/2008 Member Since: 11/19/2004 |
cool! thanks for the link paul  .......off to play with facetware.....
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| Posted: 8/2/2005 2:16:17 PM | |
| P: 8/2/2005 2:33:58 PM | |
Regular Guy Ideal Rock Total Posts: 5,321 Last Post: 11/24/2009 Member Since: 7/7/2004 |
Yes, Paul thanks. Questions and observations... How cool is this announcement to you professionals of the trade? Largely consistent with what had been expected? I'd heard John poking fun/irritation at the anticipation 5% variation for minor facets. I see what seems odd as not only a .2% variation for pavilion angle, but a commitment to keep it's validity somewhat obscured, by the promise of it only being reported on even numbers. Why not accept odd numbers and then presume .2% variation? A minor point? Re tools, where does the diamond dock fit into what GIA is offering for the trade to help? Regards, Ira (Ruffles have Ridges) Z. |
| Posted: 8/2/2005 2:33:58 PM | |
| P: 8/2/2005 2:51:57 PM | |
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Paul-Antwerp Ideal Rock Total Posts: 1,911 Last Post: 11/24/2009 Member Since: 9/3/2002 |
Basically, there is nothing that I am surprised about. The fact of rounding was sufficiently announced before, and I have reported about that quite often. I am amazed that they are really going to introduce it. I expected them to postpone it again and again, until they would shelve the whole issue. In my eyes, the whole system is a farce. If I see that a 60% table with 41.8° pavilion angle, 33° crown angle and 80% lower girdles and 50% star size scores Excellent, that is horrific. The same combination, if cut extremely symmetrically, would score AGS-5 at best in the new AGS-system. The result will be that the majority (after some adaptation, I expect at least 80%) of the rounds graded by GIA, will get an Excellent cut-grade. What is the use of all this then? Live long, Paul Slegers |
| Posted: 8/2/2005 2:51:57 PM | |
| P: 8/2/2005 2:55:34 PM | |
oldminer Ideal Rock Total Posts: 4,964 Last Post: 11/20/2009 Member Since: 9/4/2000 |
As much as we gemologists love and respect the GIA for what it has been able to accomplish over the past 60 years, one is left wondering how their "new" strategy for grading cut is going to advance the science or accuracy of graders and appraisers. I have openly been admitting for a number of years that grading by parameters is a useful screening tool, but not the final answer on how well a diamond performs. I should know, since I have been attempting to grade by parameter since before anyone seemed to care about it at all....since around 1986. When we put "Tolkowsky" cut parameter stones, or current AGS 0 round diamonds on the ImaGem machine we don't get consistent results because cutters have figured out how to squeeze a little more weight into the finished stone and sometimes this hurts light performance. The parameters look quite good, but the stone isn't so hot. Now, the GIA proposes to measure a few more angles and facet lengths, but seems to be still stuck on looking out for "pasting" and "digging" of certain facets which will have a definite effect on final light quality. I think the proposed system has benefits for cutters, but may be leaving many loopholes that will not serve consumers well. A lot of not so fine diamonds will grade "excellent". How will one select the best one if they all grade the same? It needs more discrimination. You can measure until the end of time, but there is always another variable. If you take care of round diamonds, how on earth will you be able to measure they myriad variables of fancy shapes. I think direct measurement of light performance will outshine, pun intended, any attempt to quantify beauty by looking at parameters. There are simply too many variables and when added to the inherent inaccuracy of the measuring devices they propose to use, it makes the final resultant "cut grade" doubtful. I am trying very hard to play nice! I note Paul and I were writing our responses at the same time...We seem to be saying just about the same things, too. David S. Atlas |
| Posted: 8/2/2005 2:55:34 PM | |
| P: 8/2/2005 5:12:30 PM | |
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Regular Guy Ideal Rock Total Posts: 5,321 Last Post: 11/24/2009 Member Since: 7/7/2004 |
I dunno, seems rather encouraging to me....at least from the point of view of being a consumer. Date: 8/2/2005 2:55:34 PM Author: oldminer Now, the GIA proposes to measure a few more angles and facet lengths... You can measure until the end of time, but there is always another variable. Maybe rounds are straightforward enough. So what if GIA has what's regarded as substandard analysis, for reasons of political correctness, or otherwise. If a map maker were precise in their measurements, showing where different streets were located in a country, if they make the mistake of calling each and every destination New York City, a smarter interpreter could come in, look at their data, and provide new names for the different places, without having to re-collect the data. Now, for some of you smart experts, here's a question... which would you rather have, presuming you could not do your own measuring, independent of what you are given. A map with measurements including crown & pavilion data, and a general light performance grade or a map with crown & pavilion data, along with minor facet info. For skilled appraisers, who do not have proportion measuring equipment, and when presented with options to consider from their customer...isn't that exactly what they are facing? Excluding what they may do well not to exclude...which is the diamonholder's intention when having sent the diamond to AGS...which set of data would you prefer to have? Isn't that how smart diamond shoppers will be viewing their options circa January 2006? Ira (Ruffles have Ridges) Z. |
| Posted: 8/2/2005 5:12:30 PM | |
| P: 8/2/2005 5:28:33 PM | |
Maxine Ideal Rock Total Posts: 1,394 Last Post: 10/25/2009 Member Since: 12/6/2004 |
So, now will all appraisers have to have the sarin or comparable machine to be able to measure the diamond and verify the grade???
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| Posted: 8/2/2005 5:28:33 PM | |
| P: 8/2/2005 5:57:15 PM | |
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Maxine Ideal Rock Total Posts: 1,394 Last Post: 10/25/2009 Member Since: 12/6/2004 |
Another question: If a stone is AGS0, will it most likely be a GIA exc, and vice versa????? Are the only ones who "make the grades" those w/very limited cut parameters?????
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| Posted: 8/2/2005 5:57:15 PM | |
| P: 8/2/2005 6:04:41 PM | |
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belle Ideal Rock Total Posts: 10,287 Last Post: 4/3/2008 Member Since: 11/19/2004 |
Date: 8/2/2005 5:57:15 PM maxine, the answer to that would be no.Author: Maxine Another question: If a stone is AGS0, will it most likely be a GIA exc, and vice versa????? Are the only ones who 'make the grades' those w/very limited cut parameters?????
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| Posted: 8/2/2005 6:04:41 PM | |
| P: 8/2/2005 8:14:50 PM | |
Wink Ideal Rock Total Posts: 4,033 Last Post: 11/24/2009 Member Since: 5/4/2001 |
My initial take is that many, if not MOST GIA Excellents will be no where near AGS 0's, while AGS 0's should easily score GIA Excellents. Wink (Paul will slap me up side the head and correct me if I am wrong, as will Old Miner and John Quixote...) Wink Jones |
| Posted: 8/2/2005 8:14:50 PM | |
| P: 8/2/2005 10:25:11 PM | |
Rhino Ideal Rock Total Posts: 4,865 Last Post: 11/22/2009 Member Since: 3/29/2001 |
Date: 8/2/2005 8:14:50 PM Author: Wink My initial take is that many, if not MOST GIA Excellents will be no where near AGS 0's, while AGS 0's should easily score GIA Excellents. Wink (Paul will slap me up side the head and correct me if I am wrong, as will Old Miner and John Quixote...) I've been playing with the software a bit today. Gosh is your conclusion an understatement. I have some interesting examples to post tomorrow. Rhino |
| Posted: 8/2/2005 10:25:11 PM | |
| P: 8/2/2005 10:53:03 PM | |
denverappraiser Ideal Rock Total Posts: 4,615 Last Post: 11/24/2009 Member Since: 7/21/2004 |
I also played with some stones today. Lots of excellent, nothing below very good. The old AGS scale had them ranging from 0 to 7. Hmmm. I think we are going to see cutters using a 4 step cut grading scale: AGS - 0 - For stones that can get it GIA Excellent - Most stones GIA Very Good - Stones that the cutter thought would get excellent but didnt for some reason. GIA Poor to Good & AGS 2-10 - Stones waiting to be sent to EGL for regrading This is not very different from the system that's been in place for years. AGS-0 - for stones that can get it AGS-1 for stones with AGS-0 proportions as determined by a Sarin but that failed for symmetry or polish GIA with Sarin sticker for stones that are pretty nice GIA with no Sarin Sticker for stones that are nice but where the sticker says too much EGL - all others I suspect that this is not as revolutionary a change as the labs would have us believe. Neil Beaty GG(GIA) ISA NAJA Independent Appraisals in Denver There's never a crowd when you go that extra mile. |
| Posted: 8/2/2005 10:53:03 PM | |
| P: 8/2/2005 10:59:32 PM | |
JohnQuixote Ideal Rock Total Posts: 5,212 Last Post: 5/24/2008 Member Since: 9/9/2004 |
Date: 8/2/2005 8:14:50 PM Author: Wink My initial take is that many, if not MOST GIA Excellents will be no where near AGS 0's, while AGS 0's should easily score GIA Excellents. Wink (Paul will slap me up side the head and correct me if I am wrong, as will Old Miner and John Quixote...) Claps, not slaps, Wink... Reese Witherspoon would say ‘snaps for Wink’. John |
| Posted: 8/2/2005 10:59:32 PM | |
| P: 8/2/2005 11:48:30 PM | |
strmrdr Ideal Rock Total Posts: 23,296 Last Post: 10/9/2009 Member Since: 11/1/2003 |
Am I missing something? table 56 crown 34.5 Pavilion 40.8 star 55 lower half 80% girdle med med polish - ex sym - ex Rates as only good? I had to drop the crown under 34 to get it up to VG and no combo would hit exellent?? ........... Karl has joined the diamond trade and is now posting as Karl_K |
| Posted: 8/2/2005 11:48:30 PM | |
| P: 8/3/2005 12:00:54 AM | |
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belle Ideal Rock Total Posts: 10,287 Last Post: 4/3/2008 Member Since: 11/19/2004 |
i could only get vg's as well .....guess that's why we're not in the cuttin' business strm!
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| Posted: 8/3/2005 12:00:54 AM | |
| P: 8/3/2005 12:03:16 AM | |
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strmrdr Ideal Rock Total Posts: 23,296 Last Post: 10/9/2009 Member Since: 11/1/2003 |
EDIT> iqnore this post. They are measuring the lower facets different than diamcalc does so this isnt valid. diamcalc for that combo. How is gia measuring the lowers? Same as diamcalc or the other way?  ........... Karl has joined the diamond trade and is now posting as Karl_K |
| Posted: 8/3/2005 12:03:16 AM | |
| P: 8/3/2005 12:05:24 AM | |
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strmrdr Ideal Rock Total Posts: 23,296 Last Post: 10/9/2009 Member Since: 11/1/2003 |
hca for that combo: Selected: 60% depth, 56% table, 34.5° crown angle, 40.8° pavilion angle The result is for a symmetrical diamond with a medium girdle and very good polish HCA scores were adjusted Dec. 15, 2001 and Feb. 6, 2003. Factor Grade Light Return Excellent Fire Excellent Scintillation Excellent Spread or diameter for weight Excellent Total Visual Performance 1.1 - Excellent within TIC range ........... Karl has joined the diamond trade and is now posting as Karl_K |
| Posted: 8/3/2005 12:05:24 AM | |
| P: 8/3/2005 12:09:42 AM | |
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strmrdr Ideal Rock Total Posts: 23,296 Last Post: 10/9/2009 Member Since: 11/1/2003 |
edit: not a valid image. ........... Karl has joined the diamond trade and is now posting as Karl_K |
| Posted: 8/3/2005 12:09:42 AM | |
| P: 8/3/2005 12:43:15 AM | |
Dancing Fire Ideal Rock Total Posts: 10,224 Last Post: 11/23/2009 Member Since: 4/3/2004 |
Date: 8/2/2005 11:48:30 PM strmrdrAuthor: strmrdr Am I missing something? table 56 crown 34.5 Pavilion 40.8 star 55 lower half 80% girdle med med polish - ex sym - ex Rates as only good? I had to drop the crown under 34 to get it up to VG and no combo would hit exellent?? well....if that's true,we can for the new reports to come out and buy some cheap GIA stones with those proportions.  so,even with the new report, we still need a sarin scan b/c of all these round off to the nearest what ever. 
it is always harder to find a "mind clean" stone than a eye clean stone. |
| Posted: 8/3/2005 12:43:15 AM | |
| P: 8/3/2005 1:19:16 AM | |
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Regular Guy Ideal Rock Total Posts: 5,321 Last Post: 11/24/2009 Member Since: 7/7/2004 |
I can appreciate that for those of you experts here, the story is about the analysis. And, so it should be. But, I still say that the story about the Gutenberg Bible is not about the Bible story...it's about the fact that presses were used. As Neil says: Date: 8/2/2005 10:53:03 PM Author: denverappraiser AGS - 0 - For stones that can get it GIA Excellent - Most stones GIA Very Good - Stones that the cutter thought would get excellent but didnt for some reason. GIA Poor to Good & AGS 2-10 - Stones waiting to be sent to EGL for regrading This is not very different from the system that's been in place for years. I suspect that this is not as revolutionary a change as the labs would have us believe. Neil Beaty GG(GIA) ISA NAJA Independent Appraisals in Denver The revolution is in the documenting of the data. As is noted in the tutorial, 73% of diamonds are provided with docs from GIA. Presuming this doesn't change substantially, these 73% will now have data regarding their cut, it will impact all the diamonds in the quick search...and with details on minor facets that are not provided on AGS certs. Surely, this should motivate more attention to this sort of info, and of course, that has been reviewed here before as well. To Dancing Fire...though it seems reasonable to me that more attention could be given to this ("we still need a sarin scan b/c of all these round off to the nearest what ever"), I'll bet that except for certain combinations, the detail provided will be regarded as helpful enough to specify. And to Maxine...I think the main logic is really reversed on this ("So, now will all appraisers have to have the sarin or comparable machine to be able to measure the diamond and verify the grade???"). Right now, while GIA until January includes no cut data, although most appraisers could be providing a unique and needed service, of providing this data... they don't. Come January, if they start to do this as a result of GIA's new published interest, I for one could care less. As is the case even now with appraisers who review diamonds with docs from AGS...if they have sarin and make measures that diverge from AGS, the general presumption of accuracy is with AGS...and so it would almost certainly be with GIA, as well. So, though the story is boring here, because the vendors here will routinely provide this data on their in-house options...that big database supposedly has 50,000 diamonds. That's a lot of info to be able to cull through. Isn't that the story? Regards, Ira (Ruffles have Ridges) Z. |
| Posted: 8/3/2005 1:19:16 AM | |
| P: 8/3/2005 1:42:29 AM | |
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Dancing Fire Ideal Rock Total Posts: 10,224 Last Post: 11/23/2009 Member Since: 4/3/2004 |
RG any way,i would ask for a full 3D sarin to get all the cut info.no matter is a old/new GIA/AGS report. it is always harder to find a "mind clean" stone than a eye clean stone. |
| Posted: 8/3/2005 1:42:29 AM | |
| P: 8/3/2005 6:59:54 AM | |
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strmrdr Ideal Rock Total Posts: 23,296 Last Post: 10/9/2009 Member Since: 11/1/2003 |
Date: 8/3/2005 1:42:29 AM Author: Dancing Fire RG any way,i would ask for a full 3D sarin to get all the cut info.no matter is a old/new GIA/AGS report. Same here for internet stones. However for a stone im seeing in person an ags report with angles, ideal-scope and h&a scope and a microscope/loupe would be enough. The rest of the reports would be icing on the cake. ........... Karl has joined the diamond trade and is now posting as Karl_K |
| Posted: 8/3/2005 6:59:54 AM | |
| P: 8/3/2005 9:34:56 AM | |
Detox Rough Rock Total Posts: 66 Last Post: 8/18/2006 Member Since: 5/12/2005 |
I can honestly say I wish I didn't read this thread. I am so close to purchasing a GIA EX, EX diamond with proportions that score under 2 on the HCA. These proportions are similar to those listed above. I am sure my diamond is a performer, but of course having not seen it yet, it creates one more thing to question. Of course the scientist side of me wants to investigate further. Most lilely after the purchase. 
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| Posted: 8/3/2005 9:34:56 AM | |
| P: 8/3/2005 9:42:40 AM | |
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denverappraiser Ideal Rock Total Posts: 4,615 Last Post: 11/24/2009 Member Since: 7/21/2004 |
Date: 8/3/2005 1:19:16 AM Author: Regular Guy The revolution is in the documenting of the data. As is noted in the tutorial, 73% of diamonds are provided with docs from GIA. Presuming this doesn't change substantially ... Ira, As with most things, the real battle will be over the middle ground. Other things being equal, is a GIA-excellent better (meaning more saleable) than an AGS-3? How about a GIA-good vs. an EGL-nothing? What about Imagem and the other labs that barely make the radar right now? I don’t know but this is the competitive area for the labs. More and more customers are demanding lab services and the while the percentage of stones accompanied by a report is increasing, the percentage those reports that are issued by GIA is going down. I think this is a big part of the reason that GIA is being so slow to introduce the new system. It’s almost impossible for them to win. If the category of ‘excellent’ is to narrow, their customers will flee to AGS and if it’s too broad the consumers will consider it useless. The best option is to drag their feet as long as possible. Does anyone know if the diamond dossier reports will also include the cut grade? Neil Beaty There's never a crowd when you go that extra mile. |
| Posted: 8/3/2005 9:42:40 AM | |
| P: 8/3/2005 9:47:45 AM | |
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strmrdr Ideal Rock Total Posts: 23,296 Last Post: 10/9/2009 Member Since: 11/1/2003 |
Date: 8/3/2005 9:34:56 AM Author: Detox I can honestly say I wish I didn't read this thread. I am so close to purchasing a GIA EX, EX diamond with proportions that score under 2 on the HCA. These proportions are similar to those listed above. I am sure my diamond is a performer, but of course having not seen it yet, it creates one more thing to question. Of course the scientist side of me wants to investigate further. Most lilely after the purchase. The proportions are cherry Im either missing something or the GIA software or the grading criteria are out of wack. Something strange is going on. It is way too early to hit the panic mode on this. ........... Karl has joined the diamond trade and is now posting as Karl_K |
| Posted: 8/3/2005 9:47:45 AM | |
| P: 8/3/2005 11:02:16 AM | |
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Paul-Antwerp Ideal Rock Total Posts: 1,911 Last Post: 11/24/2009 Member Since: 9/3/2002 |
Date: 8/2/2005 11:48:30 PM Hey Storm,Author: strmrdr Am I missing something? table 56 crown 34.5 Pavilion 40.8 star 55 lower half 80% girdle med med polish - ex sym - ex Rates as only good? I had to drop the crown under 34 to get it up to VG and no combo would hit exellent?? I suppose that you left the total depth at 60%. It took me about four double-clicks, but then, you can adjust the total depth. From 60.6% and higher, this proportion-set will be Excellent. Live long, Paul Slegers |
| Posted: 8/3/2005 11:02:16 AM | |
| P: 8/3/2005 1:44:48 PM | |
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strmrdr Ideal Rock Total Posts: 23,296 Last Post: 10/9/2009 Member Since: 11/1/2003 |
Date: 8/3/2005 11:02:16 AM Author: Paul-Antwerp Date: 8/2/2005 11:48:30 PM Hey Storm,Author: strmrdr Am I missing something? table 56 crown 34.5 Pavilion 40.8 star 55 lower half 80% girdle med med polish - ex sym - ex Rates as only good? I had to drop the crown under 34 to get it up to VG and no combo would hit exellent?? I suppose that you left the total depth at 60%. It took me about four double-clicks, but then, you can adjust the total depth. From 60.6% and higher, this proportion-set will be Excellent. Live long, Your right. I tried about a dozen times to change the depth and it wouldnt budge. But at 60% depth why are they knocking it down? According to diamcalc its no problem? ........... Karl has joined the diamond trade and is now posting as Karl_K |
| Posted: 8/3/2005 1:44:48 PM | |
| P: 8/3/2005 1:49:12 PM | |
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Rhino Ideal Rock Total Posts: 4,865 Last Post: 11/22/2009 Member Since: 3/29/2001 |
Date: 8/3/2005 11:02:16 AM Author: Paul-Antwerp Date: 8/2/2005 11:48:30 PM Hey Storm,Author: strmrdr Am I missing something? table 56 crown 34.5 Pavilion 40.8 star 55 lower half 80% girdle med med polish - ex sym - ex Rates as only good? I had to drop the crown under 34 to get it up to VG and no combo would hit exellent?? I suppose that you left the total depth at 60%. It took me about four double-clicks, but then, you can adjust the total depth. From 60.6% and higher, this proportion-set will be Excellent. Live long, This is very interesting Paul. Funny but when I do my searches I punch in depths that range from 60.6 - 62.2%. Rhino |
| Posted: 8/3/2005 1:49:12 PM | |
| P: 8/3/2005 2:06:40 PM | |
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strmrdr Ideal Rock Total Posts: 23,296 Last Post: 10/9/2009 Member Since: 11/1/2003 |
Date: 8/3/2005 1:44:48 PM Author: strmrdr Date: 8/3/2005 11:02:16 AM Author: Paul-Antwerp Date: 8/2/2005 11:48:30 PM Hey Storm,I suppose that you left the total depth at 60%. It took me about four double-clicks, but then, you can adjust the total depth. From 60.6% and higher, this proportion-set will be Excellent. Live long, Your right. I tried about a dozen times to change the depth and it wouldnt budge. But at 60% depth why are they knocking it down? According to diamcalc its no problem? Looks like it may be knocking it down for too thin a girdle at 60% atleast thats the only reason I can see. ........... Karl has joined the diamond trade and is now posting as Karl_K |
| Posted: 8/3/2005 2:06:40 PM | |
| P: 8/3/2005 2:32:04 PM | |
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Rhino Ideal Rock Total Posts: 4,865 Last Post: 11/22/2009 Member Since: 3/29/2001 |
Strm... for your info the lower girdle measurements given within Diamcalc are not the same that GIA is looking at. GIA/Sarin measure lower girdle length. This measurement is taken along the horizontal plane from girdle to culet and comparing the lower girdle length in relation along the horizontal plane. AGS/Helium measure lower girdle height. This measurement is taken along the vertical plane comparing the height/depth of the lower girdles in relation to pavilion depth. Note: Helium actually gives both measurements (lg height and length, along both planes). Here is the conversion chart for determining lower girdle length if you're using DiamCalc. So ... an 80% lower girdle length (length needed for new GIA Cut Calculater) would translate to 81.5% lg height in DiamCalc.  Rhino |
| Posted: 8/3/2005 2:32:04 PM | |
| P: 8/3/2005 2:41:16 PM | |
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Rhino Ideal Rock Total Posts: 4,865 Last Post: 11/22/2009 Member Since: 3/29/2001 |
Ok... playing around today a lil with the new GIA Cut Calculator. I'm finding many positives and also some negatives. One that is really throwing me for a loop is this ... Here are known poop proportions for an ideal cut and the stone DOES NOT get a GIA Grade 1. Hooray for GIA!  Rhino |
| Posted: 8/3/2005 2:41:16 PM | |
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