shape
carat
color
clarity
  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. PriceScope Upgrade Completed
    For issues, questions and comments click the link below
    https://www.pricescope.com/community/threads/pricescope-upgraded-comments-and-issues.229551/

    Dismiss Notice

It makes me wonder how acurate are those sarin and OGI...

Discussion in 'RockyTalky' started by Dancing Fire, May 12, 2004.

Thread Status:
Not open for further replies.
  1. Dancing Fire
    Super_Ideal_Rock

    Messages:
    24,805
    Joined:
    Apr 3, 2004
    by Dancing Fire » May 12, 2004
    machine. I have three different reports from three different machines on the same stone. The one from the manufacture lists the crown angle at 34.4 and PAV at 40.8. the one I recieved from the praiser, his sarin reports has a combination of 34.6 and 41 degree, and then his OGI has it at 34.2 and 40.9 degree.Even the diameter doesn''t match on any of these reports. He says you can scan the same stone three different times and you might get three different readings. The difference is the (HCA scores from 1.1-1.8)
     
  2. Magnum
    Shiny_Rock

    Messages:
    342
    Joined:
    Mar 26, 2004
    by Magnum » May 12, 2004
    That's part of the reason why you shouldn't split hairs with HCA scores below 2. The HCA really does it's best work as a sorting tool, i.e. narrowing down your search to diamonds of a certain carat/color/clarity that score below 2 on the HCA, and then using another method to pick between them.
     
  3. hoorray
    Ideal_Rock

    Messages:
    2,798
    Joined:
    May 16, 2003
    by hoorray » May 12, 2004
    Right! Even with those variances, the HCA scores show that this has the potential to be a very nice stone, so it and the various machines have done their job. Use your eyes to make the final call, not numbers[​IMG].
     
  4. niceice
    Brilliant_Rock

    Messages:
    1,792
    Joined:
    Jan 29, 2003
    by niceice » May 12, 2004
    The accuracy of the Sarin and OGI machines is only going to be as accurate as the calibration of the machine, some dealers calibrate their machines more frequently than others, we calibrate ours on all three channels to "master stones" at the beginning of every week and re-calibrate the machine during the week if we suddenly notice a major variance. Also, a single speck of dust on the diamond can really wreak havoc in terms of the results because everything is inter-related...

    But to answer your question, there is a variance between the machines... We forget what the advertised tolerance is, but seem to recall that Garry Holloway mentioned it on another thread awhile back... Was it 0.02% or something like that?

    You can actually get slightly different, but similar results on the same machine when measuring a diamond and then removing it from the machine and measuring it again... The less expensive versions of the machine produce less accurate results than the more expensive versions of the machine which is why we tend to look sideways at the results provided by dealers who are using that dinky little countertop version, as we understand it, it is a difference in the quality of the optics...
     
  5. Richard Sherwood
    Ideal_Rock

    Messages:
    4,924
    Joined:
    Sep 25, 2002
    by Richard Sherwood » May 12, 2004
    The more money the Sarin or OGI costs, the more accurate it is. The range of accuracy tightens up quite a bit with a $20,000 Sarin (which most jewelers don't have) versus a $6,000 Sarin (which is the most common model sold).

    Even for the lower priced Sarins & Megascopes, the accuracy is quite good, considering. You're talking about hundredths of degress and mm's, with the results coming out relatively close.

    Just ten years ago, this kind of accuracy was unobtainable. Now it's common, and improving daily. Five years from now (probably one year) you'll see considerably tightened measurements.

    If all the machines tell you that you have an ideal cut stone that scores less than 2.0 on the HCA, then you know you're in good territory, confirmed three times over.
     
  6. Garry H (Cut Nut)
    Super_Ideal_Rock
    Trade

    Messages:
    13,875
    Joined:
    Aug 15, 2000
    by Garry H (Cut Nut) » May 12, 2004
    I agree with everything said above.
    Just consider you are measuring angles on things with 3mm or 1/10th an inch to less than 1 degree - is that amazing, or B..... Amaaaazzzzzing!!!!

    And please use HCA as a rejection criteria, not a selection criteria [​IMG]
     
  7. Rhino
    Ideal_Rock
    Trade

    Messages:
    6,058
    Joined:
    Mar 28, 2001
    by Rhino » May 12, 2004
     
  8. Garry H (Cut Nut)
    Super_Ideal_Rock
    Trade

    Messages:
    13,875
    Joined:
    Aug 15, 2000
    by Garry H (Cut Nut) » May 12, 2004
    I agree with everything said above.
    Just consider you are measuring angles on things with 3mm or 1/10th an inch to less than 1 degree - is that amazing, or B..... Amaaaazzzzzing!!!!

    And please use HCA as a rejection criteria, not a selection criteria [​IMG]

    Have a look here for the next generation - it is not available outside Russia and India yet (because there is no service agents elesewhere just as yet.
    www.octonus.ru/oct/products/helium/

    This raises the level of accuracy to a new level - it was a requirement of the OctoNus need to build accurate 3D models for our new cut grade approach. It is more expensive, and at this stage has a small fixed lens, but the target market usually operate with many diferent sized lenses and changing lens introduces innaccuracies.
     
  9. Rhino
    Ideal_Rock
    Trade

    Messages:
    6,058
    Joined:
    Mar 28, 2001
    by Rhino » May 12, 2004
    I've been checking out that page Gary. I especially like it's import feature into the new DiamCalc 2.3 and DAYUM... those reports.
     
  10. niceice
    Brilliant_Rock

    Messages:
    1,792
    Joined:
    Jan 29, 2003
    by niceice » May 12, 2004
    Will your new toy be at JCK Vegas Garry? The term "toy" intended affectionately [​IMG]
     
  11. Garry H (Cut Nut)
    Super_Ideal_Rock
    Trade

    Messages:
    13,875
    Joined:
    Aug 15, 2000
    by Garry H (Cut Nut) » May 12, 2004
    R&T, this will not be sold in USA unless we can find a service agent distributor etc.

    The report probably will not format properly, but below is the data:
    Illustrated report for finished diamond
    Model KB7 Symmetry
    Expert name Savrasov S.
    Report date 03.03.2004 Polish
    Real weight ct 0.3760
    Calc. weight ct 0.3758 Color
    Measurements mm 4.776 (4.761-4.790) x 2.719
    Spread ct 0.03 8.30% Clarity
    C-Hgt P-Dpth Table Culet G-bzl G-bone G-val
    Average values mm 0.547 2.043 3.061 0.025 0.138 0.160 0.076 Fluorescence

    Fish eye effect ° 3.50 N/A EF / Nat Yes (2)
    Culet thr bezel ° 25.33 N/A

    Parameter 1 2 3 4 5 6 7 8 Avg Min Max Dev Cut Sym
    Diameter mm 4.783 4.773 4.774 4.774 4.776 4.761 4.790 0.59% N/A EX
    Crown angle ° 32.40 32.53 32.07 30.98 32.40 32.27 32.56 32.46 32.21 30.98 32.56 1.58 G VG
    Upper angle ° 39.36 39.07 39.49 40.33 39.95 39.44 39.10 39.86 39.78 38.86 40.93 2.07 - GD
    40.79 38.86 40.87 40.05 40.93 39.45 39.34 39.66
    Star angle ° 19.40 19.54 19.23 18.59 17.62 18.58 18.13 20.05 18.89 17.62 20.05 2.42 - GD
    Pav angle ° 40.35 40.34 39.72 40.22 40.78 41.38 41.46 41.01 40.66 39.72 41.46 1.74 N/A VG
    Halves angle ° 41.10 41.12 41.11 40.61 40.68 41.02 41.37 41.58 41.55 40.61 42.41 1.80 - VG
    41.81 42.23 42.37 42.41 42.21 41.98 41.78 41.35
    Total height % 56.93 N/A
    Crown height % 12.31 12.11 11.63 10.89 10.85 10.67 11.23 11.91 11.45 10.67 12.31 1.64 N/A VG
    Pav depth % 41.71 42.30 42.05 43.08 43.57 43.88 43.38 42.24 42.78 41.71 43.88 2.17 G GD
    Table % 64.14 64.23 64.19 63.81 64.09 63.81 64.23 0.41 F EX
    Culet % 0.53 0.35 0.64 0.29 N/A EX
    Girdle Bezel % 2.90 2.52 3.39 3.22 2.76 2.53 2.63 3.09 2.88 2.52 3.39 0.87 E-VG EX
    Girdle Bone % 3.12 3.49 3.50 3.14 3.82 3.02 3.57 3.07 3.34 3.02 3.82 0.79 EX
    Girdle Valley % 1.48 1.31 1.43 1.96 2.00 1.84 1.75 1.40 1.59 1.25 2.00 0.76 N/A EX
    1.71 1.38 1.37 1.25 1.48 1.76 1.74 1.59
    Star : Upper ratio % 54.56 : 45.44 58.02 : 41.98 60.32 : 39.68 58.57 : 41.43 63.46 : 36.54 60.39 : 39.61 57.91 : 42.09 54.04 : 45.96 58.41 : 41.59 54.04 : 45.96 63.46 : 36.54 9.41 - PR
    Crown azimuth ° 359.9 45.7 89.6 134.7 177.8 226.3 270.1 318.2
    Pav azimuth ° 0.0 45.5 90.6 136.6 181.5 225.6 270.2 315.3
    Twist ° 0.08 0.17 0.95 1.95 3.69 0.71 0.08 2.83 1.31 0.08 3.69 3.62 - VG
    Appraiser GIA
    Overall F PR
    Total height mm 2.719
    Crown height mm 0.588 0.578 0.555 0.520 0.518 0.510 0.537 0.569 0.547 0.510 0.588 0.078 - -
    Pav depth mm 1.992 2.020 2.008 2.058 2.081 2.096 2.072 2.017 2.043 1.992 2.096 0.104 - -
    Table mm 3.063 3.067 3.066 3.048 3.061 3.048 3.067 0.020 - -
    Culet mm 0.025 0.017 0.030 0.014 - -
    Girdle Bezel mm 0.139 0.120 0.162 0.154 0.132 0.121 0.126 0.148 0.138 0.120 0.162 0.041 - -
    Girdle Bone mm 0.149 0.167 0.167 0.150 0.182 0.144 0.171 0.147 0.160 0.144 0.182 0.038 - -
    Girdle Valley mm 0.071 0.062 0.068 0.094 0.096 0.088 0.084 0.067 0.076 0.059 0.096 0.036 - -
    0.081 0.066 0.065 0.059 0.070 0.084 0.083 0.076
    Measurement as per OctoNus theory:
    Crown angle ° 32.40 32.40 32.32 31.72 32.21 31.72 32.40 0.68 - -
    Pavilion angle ° 40.56 40.86 40.59 40.62 40.66 40.56 40.86 0.30 - -

    Helium snap.jpg
     
  12. Rank Amateur
    Brilliant_Rock

    Messages:
    1,553
    Joined:
    Feb 26, 2003
    by Rank Amateur » May 12, 2004
    Garry

    Have you run numbers on the + - accuracy of the HCA given a certain + - accuracy of the input? It's something I've always been curious about.

    R/A
     
  13. Garry H (Cut Nut)
    Super_Ideal_Rock
    Trade

    Messages:
    13,875
    Joined:
    Aug 15, 2000
    by Garry H (Cut Nut) » May 13, 2004
    It is easy for you to see for yourself RA - especially now we have the new charts up.
    It is not critical in the sweet spots - or in the really bad spots - it is more critical in the transition regions like that in the case for this thread.

    Have a look - you can do your own #'s very easily [​IMG]
     
  14. valeria101
    Super_Ideal_Rock

    Messages:
    14,069
    Joined:
    Aug 29, 2003
    by valeria101 » May 13, 2004
    Good Lord [​IMG] How many number can one make dance on the pointy culet of a diamond!

    Does the HCA consider this "averging out" (and hence the symmetry grade, I guess) anywhere in the fine print? Not that it isn't hard enough to detter hair splitting as is... but it shouldn't be Hell to incorporate sone degree of approximation.

    The charts definitely help visualise what the variation of those stats do to a score, but one would still start generating PS threads when an unfortunate stone appears ambiguous - as non AGS0 do... And this is not a tool meant to promote AGS's opinion, as far as I understand.
     
  15. CaptAubrey
    Brilliant_Rock

    Messages:
    863
    Joined:
    Mar 28, 2004
    by CaptAubrey » May 13, 2004
    i think if you show a report like that to the average diamond buyer, they're going to run screaming out of the store in terror.




    there's such a thing as too much information...
     
  16. mdx
    Brilliant_Rock

    Messages:
    570
    Joined:
    Mar 1, 2002
    by mdx » May 13, 2004

    Hi CaptAubrey

    I think you will find that in the real world the majority of diamond consumers have no interest in the numbers

    They are looking for the visual result of the good numbers.
    This results in extreme frustration for our sales staff who are trained to expound the gospel of the ideal cut and the symmetrical beauty of the mighty hearts and arrows. If however a consumer shows even the slightest interest in the numbers we vent our frustration by bombarding them with every conceivable report known to man.

    Any chance of a service agent in Australia Gary, This looks like a must have.

    These advances in technology must however be of great interest to manufacturers and dealers who produce and sell better quality goods.
    We are going into exciting times as cutters use these technologies to explore the possibilities of the non-traditional ideal cuts creating balance in yield and beauty.

    And so we will go on expounding the gospel, but now for a wider range of beauties.

    Johan
     
  17. Rhino
    Ideal_Rock
    Trade

    Messages:
    6,058
    Joined:
    Mar 28, 2001
    by Rhino » May 13, 2004


    ROFLMAO ... my assistant said the same thing in so many words. It is a very scientific report and gives details most here would not understand. What would make it more challenging is being able to interpret how those numberes correlate to real world observance. Something that very few gemologist's can do especially when it comes to nuances in the minor facet details.
     
  18. Garry H (Cut Nut)
    Super_Ideal_Rock
    Trade

    Messages:
    13,875
    Joined:
    Aug 15, 2000
    by Garry H (Cut Nut) » May 13, 2004
    Rihno tht is exactly what the outcome of this conference is - how to scan a diamond and bypass the numbers to a cut grade [​IMG] You should have been there - you will regret it [​IMG]

    Ana re AGS - they will have a system that looks somewhat like HCA charts, but with very tight cut offs, like no stones under X crown angle (but way lower than 33.8) and they will not have anything that does not look good from 10 inches 25cm (which means the shallower HCA stones will not make it (they look good from 14 inches or 35 cm.) 1ct stones would need to be between say 6.4 and 6.6mm etc etc - very strict stuff.

    Johan, yes we (CP) will be able to supply and service Helium down under.
     
  19. Dancing Fire
    Super_Ideal_Rock

    Messages:
    24,805
    Joined:
    Apr 3, 2004
    by Dancing Fire » May 13, 2004
    Ana re AGS - they will have a system that looks somewhat like HCA charts, but with very tight cut offs, like no stones under X crown angle (but way lower than 33.8) and they will not have anything that does not look good from 10 inches 25cm (which means the shallower HCA stones will not make it (they look good from 14 inches or 35 cm.) 1ct stones would need to be between say 6.4 and 6.6mm etc etc - very strict stuff.

    Johan, yes we (CP) will be able to supply and service Helium down under.
    ----------------[/quote]

    cut nut

    if we're not careful what we buy(today) the premiun you pay for a AGS 0 cut may not be a AGS 0 cut tomorrow.
     
  20. Garry H (Cut Nut)
    Super_Ideal_Rock
    Trade

    Messages:
    13,875
    Joined:
    Aug 15, 2000
    by Garry H (Cut Nut) » May 13, 2004
    Yes
    But if you listen carefully you can buy today a diamond for less, that will tomorrow be an AGS 0 [​IMG]
     
  21. Rhino
    Ideal_Rock
    Trade

    Messages:
    6,058
    Joined:
    Mar 28, 2001
    by Rhino » May 13, 2004


     
  22. Rhino
    Ideal_Rock
    Trade

    Messages:
    6,058
    Joined:
    Mar 28, 2001
    by Rhino » May 13, 2004
    Gary ... do you know what seperates the most expensive Sarin's from the least? From what I've been told it's the resolution of the camera used. Most models use a 320 x 240 scanning rez while the most expensive model uses 640 x 480, being able to get much higher detail and accuracy. Have I heard correctly and is there any other technical difference I should know about?




    Also, what is the resolution of the Helium scanner?




    Regards,
     
  23. jasper
    Rough_Rock

    Messages:
    90
    Joined:
    Sep 16, 2001
    by jasper » May 14, 2004
    Leonid, Valeria, or Garry,

    What is the URL for the page(s) with the new HCA charts? Valeria reposted one of them on another thread:
    https://www.pricescope.com/idealbb/files/flatsd.JPG
    but I cannot find any of the others, nor can I find the fine print for the chart. (For example, preparation date, any penalties left out of the chart, table size, et cetera.)

    -- Jasper
     
  24. strmrdr
    Super_Ideal_Rock

    Messages:
    23,295
    Joined:
    Nov 1, 2003
    by strmrdr » May 14, 2004
    YES!!!!
    I want that much data on the next diamond I purchase!!
    While some of is likely not to be too usefull to me, can you imagine the look on someones face when they ask about the diamond and you pull that chart out!!
    Even better pull it out in a jewlery store and tell the jewler that I have a question on a report I got on the diamond im considering!!!!!!
    hehehehehehehehehehe
    hmmmmm
    even better would be at a maul store I can just see the clerk going into sensory overload and the DUH light come on!

    Rhino can you get one in time to use on the diamond we just talked about???????
    please!!!!!!
    ROFL!!!!


    btw is there a website with more listings and an explaination of some of it?


    ps. the diamond we talked about is a whole 2mm wide! so it will have to be the one after that.



     
  25. Garry H (Cut Nut)
    Super_Ideal_Rock
    Trade

    Messages:
    13,875
    Joined:
    Aug 15, 2000
  26. pricescope
    Ideal_Rock

    Messages:
    8,266
    Joined:
    Dec 31, 1999
    by pricescope » May 14, 2004
    Hi Jasper, there are several charts for each table size (from 53% to 65%) like that one. You can see them when enterring different table size in HCA.

    [​IMG]
     
  27. Rhino
    Ideal_Rock
    Trade

    Messages:
    6,058
    Joined:
    Mar 28, 2001
    by Rhino » May 15, 2004


     
Thread Status:
Not open for further replies.

Share This Page