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warping

Discussion in 'RockyTalky' started by bdgr4evr, Apr 10, 2001.

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  1. bdgr4evr
    Rough_Rock

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    by bdgr4evr » Apr 10, 2001
    A question for all:in the process of learning about diamonds on the net and locally, it appears that most of the diamond dimensions I see dont add up..ie total depth vs. crown , pavillion and girdleIs the warping explanation for this fact, an opinion or a truth....if it is a truth, do the stones automaticallly fall into aga III category.....should i be as concerned/alarmed as I am...im lookin for an AGS 000 2 ct E round stone...the prices im finding scare me to death given the warping issue and the potential to really be taken.....MR Holloway, what is your opinion on this issuethanks alotdan becker
     
    


    


  2. Ghost_In_The_Net
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    by Ghost_In_The_Net » Apr 10, 2001
    Dear people of this forum,My name Is Liron And I am the Customers Support person In Sarin Technologies Ltd.I need to rectify on the subject discussed here. I haven't heard of the term "Warped" Diamonds and It seems unlikely there is one.In any case, The reason that when measuring in the Sarin machines the Sum of Pavilion height, Girdle thickness and Crown height don't add up to the Total depth is due to one reason. Each institute measures a different part of the girdle. AGS and AGL institutes grade the girdle by the valleys.
    HRD on the other hand grades the Girdle by the Bezzels and If you'll check in the Sarin machine in the HRD institute you would see the in fact the velues do add up. For any other question on the Sarin Machines or counceling please contact me at my Email.Have a nice day you allLiron
     
  3. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Apr 11, 2001
    Thanks for the clarification Liron. I made this comment referring to that issue, but my knowledge is not as concise as yours
    My quote from above was
    "But also because the girdle thicknes varies (16 thin and 16 thick spots in a wavy line) diferent gem lab systems get different total depth %'s for the same stone."Regards Garry
     
  4. lawmax
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    by lawmax » Apr 11, 2001
    Thank you Liron [​IMG]
     
    


    


  5. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Apr 11, 2001
    Warping is an issue invented by mr Cuellar to sell his diamonds. No one else has unwarped diamonds.
    The #'s dont add up because of some reasons i dont have time to explain. But it is not sisnister. But Fred C is.
    gh
     
  6. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Apr 11, 2001
    If you use HCA you can find non AGS 0's with GIA papers at less $'s that are often better than AGS0's
     
  7. bdgr4evr
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    by bdgr4evr » Apr 11, 2001
    Mr Nut: Thanks for the help...without throwing mud could you help a lay person understand all the issues with Mr "c"...is he a maverick out to destroy the profitability of industry distribution chain or is he mathematically and optically misinnformed...obviously he has a vested interest in selling his diamonds, but for nomal people like us w ho dont specialize in your field, its hard to tell the truth from the marketing gimmics...after all we are dealing with very high profitablity for the distribtion chain and a very low level of consumer knowledge....any articles or web sites you can point me too....i dont mind techical reading, and actaullly prefer it..thanks again
     
  8. pricescope
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    by pricescope » Apr 11, 2001
    I'm not aware of any reliable ways to estimate crown and pavilion angles based on the table and total depth.Sarin or Ogi measurements are not expensive at all. Most of the diamond cutters have the machines. Besides, you shouldn't have a problem finding gemological lab that has them.You can find some excellent stones outside AGS0 using www.pricescope.com/sift.asp
     
  9. pricescope
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    by pricescope » Apr 11, 2001
    Bdgr4evr,Garry is not throwing mud [​IMG] It was just very late in Australia when he posted.For my understanding, there are certain measurements limitations of the Sarin machines and the way Sarin present the data that lead to contradiction between total depth and crown, pavilion and girdle depths %. Mr. Cuellar calls diamonds with this contradiction "warped".Garry knows Sarin machines very well and I hope he will explain the problem in details.I also sent a request to Sarin.
     
  10. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Apr 11, 2001
    Sorry Dan,
    Leonid was right It was late. Sarin Technologies and Ogi Corporation both manufacture proportion-measuring devices. The base models from both companies have limited accuracy but more advanced models incorporate multi lens systems that use a larger portion of the field of view to measure different size stones. Measuring a 3mm stone with a lens designed to measure 20mm diamonds reduces the accuracy by a factor of three compared to using a lens designed for a 7mm maximum stone diameter.
    Sarin claim accuracy of 20 microns or ±0.2 degree.
    The Sarin system measures facet inclination by plotting interceptions. Shorter facet edges have a greater margin for error. It follows then that the crown angle has the more than twice the potential error when compared to pavilion facets. However pavilion angle is four or five times more critical than crown angle in its effect on Cut Adviser scores (and diamond performance) or any other proportion in its effect on diamond beauty. Assume a tolerance of .2 degrees in crown angle measurements a maximum and this provides a limiting factor for accuracy of plus or minus 0.4 variation in scores using the Cut Adviser.Many observers note that Sarin proportions often do not add up to the same total depth as calculated by dividing depth by diameter. This is partly because Sarin measure angles and then 'calculate the %'s. But also because the girdle thicknes varies (16 thin and 16 thick spots in a wavy line) diferent gem lab systems get different total depth %'s for the same stone. All the real experts in the tade know this and ignore it because they take no notice of Freds observation. The solution applied by Ogi is to adjust measured parameters to equal the known depth percentage, but this aalso changes the results. This equates to a surveyor adjusting rise and fall measurements to ‘close the loop’, an approach that adds an error to the measured proportions, rather than accepting the best assessments of the instrument. All the major laboratories choose to use Sarin devices.So Fred has been using this info to scare customers away from other vendors stones. Now be aware we are not selling you a stone, we are giving you free information, and i am a busy boy. I have never met Fred but the stories I hear make my hair curl. He cant sue me either because there are hundreds of people who would act as witnesses.You cant use table and depth % for anything useful. Look at the 60:60 section of the tutorial.
    garry
     
    


    


  11. pricescope
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    by pricescope » Apr 11, 2001
    Another point Garry is trying to make is that light performance of the diamond depends upon angles, not the depths.Pavilion angle is the most important because light should be reflected twice from the pavilion facets. Fortunately, pavilion angle is the most accurate parameter measured by Sarin machines.
     
  12. bdgr4evr
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    by bdgr4evr » Apr 11, 2001
    thank you Garry!
     
  13. bdgr4evr
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    by bdgr4evr » Apr 11, 2001
    thanks for the help leonid:another follow up if i may;mr holloway suggests if the total depth is on the high side, ie the pavaillion is too deep there does exist crown angles that compensate for the improper pavillion angles...is it often the case that these stones witht the proper compensating angles can be found or are they rare....can adequate angles be approximated if you only have the basic GIA data and not the sarin machine or megascope..most of the retailers and wholesalers i talk to dont have the m achines and suggest the appropriate data can be derived from the basic GIA data points
    thank for the helpdan becker
    overland park ks
     
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