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EVOLUTION OF THE IDEAL CUT

Discussion in 'RockyTalky' started by michaelgem, Jan 17, 2008.

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  1. michaelgem
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    by michaelgem » Jan 17, 2008

    Ideal Evolution


    Ever wonder why a large majority of diamonds are cut and polished as 58-facet round brilliants? Why are top quality round brilliants referred to as American Ideal, Tolkowsky Ideal or just Ideal Cut? Al Gilbertson asked those questions back in 1976, the first day on the job as faceter for an American Gem Society (AGS) jeweler. Al's subsequent jewelry career spans over 30 years as gemstone cutter, then jeweler, independent gemologist-appraiser and finally researcher in cut grading at the Gemological Institute of America (GIA). Today, Al presents us with the definitive answers to these questions in his new book just out: "American Cut - The First 100 Years."

    Everyone, from those just learning about the Ideal Cut to the "diamond mavens" among us, will appreciate the significance of this historically important research on the evolution of the American Ideal Cut. The publication of Al's book presents a great opportunity to set the record straight for the diamond and jewelry industry concerning the "myths" surrounding the origins of the Ideal Cut. Al's exhaustive research is the last and best word on this subject. It has added significance due to its publication by the GIA and endorsement by GIA's president Donna Baker and chairman Ralph Destino. Donna wrote, "This important work will change your understanding of how and why diamonds are cut the way they are today." Ralph added, "The book is clearly the definitive text on the subject and, as such, will have genuine lasting value in gemological history." Clearly, GIA's endorsement of Al's research through publication of his book is an indication of their wish to set the record straight and correct the myths concerning this most important and most popular of diamond cuts.


    Chief among the discoveries you will make in this great read is that the Ideal Cut of today evolved from uniquely American origins, beginning with Henry Dutton Morse of Boston in the 1860's.

    "The myth is that the American Cut was created by Marcel Tolkowsky. Many believe that the cutting style he wrote about was his "ideal," and that somehow he only saw a narrow set of proportions as the best." says Gilbertson. He points out that Tolkowsky himself did not call it "ideal," and that he did indeed see other widely ranging proportions he thought had been cut to "obtain the liveliest fire and the greatest brilliancy." This should give everyone pause. Al goes on to say: "While Tolkowsky's influence did modify the American Cut's table size, he was not the first to advocate many of the proportions proposed in his book. That started in the late 1800s with Henry Morse in Boston, who wanted to cut diamonds for beauty, not weight. The story of Morse, and later Frank Wade, the industry trade press and GIA founder Robert M. Shipley's influence on cut, has, until now, been obscured by the Tolkowsky myth." Al's vision for his book was to share the real evolution of the American Cut and in doing so, "credit all of the diamond cutters and industry advocates who contributed to what many think are the best proportions to make a diamond sparkle."

    I expect many in the trade to continue perpetuating the marketing myths that attribute the Ideal Cut solely to Marcel Tolkowsky and his single combination of theoretical angles. But after reading the rich history uncovered by Al's work, and perhaps doing a little research of their own using his large bibliography of references, many others will replace the myths with an even richer reality.

    In talking to Al about his research for the book, I learned that GIA, AGS and the cutting firm of Lazar Kaplan (LK) were early promoters of the Tolkowsky theoretical pavilion and crown angles of 40.75 degrees and 34.5 degrees, attributing them to what they called the American Cut and the Ideal Cut. Curious about the early beginnings, Al talked to some of the early pioneers in diamond cutting, including George Kaplan. George had no recollection of LK cutting to Tolkowsky's proportions until they became active with GIA and AGS. George thought that this was in the late 30's, years after Tolkowsky's book. Al's research turned up (limited) articles from that time about LK. Supporting Kaplan's recollections, the articles did not mention the Ideal or Tolkowsky. Interestingly, the term Ideal cut, referring to a round brilliant that was cut to Morse's angles (with a smaller table than Tolkowsky), appeared in American literature decades earlier (Cattelle, 1903).

    So, as Al's book carefully documents, the most important angles associated with the Ideal Cut began with Henry Morse and subsequent supporters and cutters who used his pavilion and crown angles in attaining the Ideal in round brilliant diamond cutting.

    I view Al's book as a factually supported, exhaustive, historical account of the evolution of the American Ideal Cut diamond, and hope that many will read it, gaining insight into these issues.

    To learn more about Al Gilbertson and the significance of his research on the evolution of the American Ideal Cut see his video on YouTube:

    http://www.youtube.com/watch?v=2kc79FY0Obg


    Also, go to:

    http://www.podshow.com/player/psp.php?theFeed=insidegiaedu&theEpisode=87910


    for an audio presentation of a reading from Chapter 2. There you will be introduced to Henry Morse, the Book's central figure.


    Other views and reviews of Al's book can be found at:

    http://www.jckonline.com/article/CA6495635.html?industryid=668 by Gary Roskin, JCK

    http://journal.pricescope.com/Articles/53/1/American-Cut---The-First-100-Years%2c-by-Al-Gilbertson%2c-GG.aspx by John Pollard, Whiteflash

    http://gemwiseblogspotcom.blogspot.com/ by Richard Wise, Wise Goldsmiths

    Michael D. Cowing FGA
     
    


    


  2. Skippy123
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    by Skippy123 » Jan 17, 2008
    Thanks for the information; this should be some interesting reading and viewing.[​IMG][​IMG] Where could we see a picture of the American cut? Intereting info on the "Idea cut" and the history, thanks!
     
  3. Lorelei
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    by Lorelei » Jan 18, 2008
    Thanks Michael![​IMG]
     
  4. oldminer
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    by oldminer » Jan 18, 2008
    Thanks Michael. Does the book give a reason why 8 sided symmetry is so popular in round diamonds? I see there are some 10 sided stones out there which look very good yet have not become popular. The ten-fold symmetry ones might be very strong perfromers in larger sizes, bu it is just an intuitive guess on my part.
     
    


    


  5. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Jan 18, 2008
    Dave I think I can say for Michael, the book does not.
    But the answer is most diamond crystals have 4 fold symmetry, and patterns of 4 (baguettes, emerald cut and princess) make economic sense.
    But rounds fetch more $$$$ so 8 fold also makes sense.
    10 is a case of "some is good, more must be better" like Leo et al. But as we know more is only better in very large stones .
     
  6. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Jan 18, 2008
    Ideal as a concept has ground our industry into a very tight spot between a rock and a very hard place.
    Al has written an interesting book with loads of work and research.
    I doubt that it could or should ever be "the last word" or any such thing as the best word.

    Because you assume that such an ideal is "good".

    Others, who might not be so patriotic, consider a loss of opportunity to be the direct result of this type of thinking.

    Which is not to say that America did not bring major open minded innovation to diamond cutting. But it has taken a long time to make the round brilliant look good - it really was not until 1/2 a century later that the better lower girdle facet length was optimized.
    Hardly rapid technological development?
    Those who placed a big emphasisi on the facets that cover more than 1/2 the diamonds surface seem to neglect that when it suits some alternative purpose?

    Meanwhile we have this problem to solve
     
  7. diagem
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    by diagem » Jan 18, 2008
    Thank god demand for very large rounds is much lower than demand for very large fancies...[​IMG]
    other wise we would encounter loads of flashing headlights out there...[​IMG]

    Also..., depending on the lgf''s..., a cutter can control the splinter like fire effect that comes out of a round (make the flashes/fire thiner or wider...)
    I assume a cutter would loose that control when cutting 8-10 folds..., even in very large rounds...
     
  8. diagem
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    by diagem » Jan 18, 2008
    In the mean time..., I cant help notice the fact that commoditization of the round brilliant (or any other shape) is NOT taking off!!!

    So far (I must add...), but I really doubt they will////[​IMG]
     
  9. strmrdr
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    by strmrdr » Jan 18, 2008
    Good points.
    I love super-ideal rounds but in fancies other than maybe princess cuts(which I don''t care about and haven''t studied) its evil.
    Take asschers for example there are many many ways too cut kicken asschers.
    AGS system doesn''t take that into account and really cant because the numbers that make a kicken asscher can also make a crappy one.
    What they came up with is an uneconomical system that isn''t in tune with today''s cutting needs that does not and can not take into account the most important things that make for a kicken asscher. I expect the EC system too be more of the same.
    While an aset is nice as one step in the buying tool chain it is not and never will be the final answer, mainly because asschers are very very head shadow sensitive and one that works at one level of head shadow might not work at another.
    Humans will move the stone until they see what they want too see no machine can do that.

    Rounds in my opinion are a much more forgiving cut because of the light return that they are all about. They are the headlights of the diamond world where fancies are the movies of the diamond words putting on a show that isn''t about pure light return power.

    As far as lgf% goes a better way of saying it is that matching it too the c/p angle is the real innovation.
    OEC and the way they are cut is kicken with very short lgf%, where more modern combos need a longer lgf%.
    I feel that may actually be a more innovative change than the c/p angle change.

    The idea of patenting gemstone cuts when applied to diamonds then marketing the heck out them was a stupid idea from the start that was out of tune for a still very traditional e-ring market and very few of them took the time and $$$ too do it right.
    Finding the right combo of yield, performance and looks to make a "new"* cut catch on is a long hard battle.
    * new too diamonds, old news too gemstone cutters.

    I''m looking forward too eventually adding Al''s book too my library after reading his work on the net it should be a well researched and well written work.
     
  10. strmrdr
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    by strmrdr » Jan 18, 2008
    You may be looking at it wrong the more facets than RB cuts are all about controlling the light return if done right.
    For example the Solasfera uses c/p angles in the shallow/steep range when cut 8 fold which would create a very directional bright stone with little life or in some combos a bright but leaky one(the 10 fold allows for deeper pavilions while avoiding leakage).
    Then they divide that light return into smaller chunks and send it out more directions too add life back in.
    This also improves yield so the cutters win also.
    Excellent engineering if you ask me, the pricing and marketing leaves something to be desired however, there is no real reason they should have as much a premium as they do.
    Busy in small sizes but comes into its own in larger sizes.
     
    


    


  11. JohnQuixote
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    by JohnQuixote » Jan 18, 2008
    The book is a great read. Al''s dedication to finding and sharing the many details is remarkable. Thanks for mentioning the journal article Michael.


    I suspect the trade needed time to react to the change from gas to electric lighting in common viewing environments Garry (not to mention the resistance ''scientific'' cutting encountered for many decades).
     
  12. strmrdr
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    by strmrdr » Jan 18, 2008
    good point and one that I agree with and have made many times, the lighting is driving the cut evolution.
    As lighting changes too very soft cft lighting indoors I think it will change again eventually.
    The movie type cuts which is a lot of ways can include h&a will pick up steams vs pure light return I think.
    This is actualy a good topic for a new thread.

    edit: https://www.pricescope.com/community/threads/mandated-cft-and-the-diamond-cut.76655/
     
  13. michaelgem
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    by michaelgem » Jan 18, 2008

    Charles L. Wells comments: I am not aware of any "myths" about Henry Morse''s cut and Tolkowsky''s later "blueprint". Shipley''s teachings of the 1950''s clearly documented the Morse origin of the American Cut, and of Tolkowsky''s later study of it. Tolkowsky didn''t invent it, nor did he claim to - he just documented it fairly accurately, but with minor variations. Nothing "new" about this! CLW


    His negative reaction to the review of Gilbertson''s book: "The American Cut - The First Hundred Years" presents an opportunity for clarification.


    There is no intent to diminish Tolkowsky''s important contributions to the evolution of the Ideal Cut. The problem, which Gilbertson dubs a myth, is the belief spread by GIA and AGS education that there was a single peak in diamond light performance or beauty at Tolkowsky''s theoretical 40.75 pav angle, 34.5 crown angle and 53% table. These proportions are indelibly etched in every textbook on the subject and in every reticule of every GIA Diamond Proportion Analyzer. As is carefully addressed in Gilbertson''s book and my review: "The myth is that the American Cut was created by Marcel Tolkowsky. Many believe that the cutting style he wrote about was his "ideal," and that somehow he only saw a narrow set of proportions as the best."


    The belief in the superiority of Tolkowsky''s theoretical angles and table size is further evident in GIA and AGS writing and course work that use American Ideal and Tolkowsky Ideal interchangeably. They never refer to the American Ideal as the Morse Ideal. For example, the GIA diamond course from 1993, on the page titled "The Quest for the Ideal" points out: "Although Diamond Design was first published in England, Tolkowsky''s design is often called the American Ideal Cut, because US cutters were the first to adopt it. ... For years, GIA used the American Ideal Cut as the basis of a comparison system in teaching diamond cut evaluation."


    The world of diamond cutting has long since rejected 53% as an optimal table size. I and others have made the case that a 41-degree pavilion angle, first espoused by Morse, is as good or better a center point for the range of pavilion angles that today are considered Ideal.


    Thanks for the opportunity to clarify.


    Michael D. Cowing FGA


    PS: For Skippy, here is my signature Ideal Cut photograph from my website:


    signitureideal.jpg
     
  14. shel
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    by shel » Jan 18, 2008
    What you say about the 41 degree pavilion as a center point is interesting. I wonder if AGS might be coming around to that idea. They graded this diamond with a 41.2 degree pavilion (and 34.9 degree crown, 56% table, 61.9% depth) as being zero for light performance. It''s nice to know that parameters not typically considered ideal can still perform well, according to the AGS; the same parameters score a not-so-hot 3.4 on the HCA.

    link to diamond and AGS report:
    http://www.jamesallen.com/diamonds/I-SI1-Ideal-Cut-Round-Diamond-973371.asp?b=16&a=12&c=77&cid=131
     
  15. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Jan 18, 2008
    Can anyone tell me when electric lighting took over from gas lighting in homes and at work?

    Michael you do know that all proportions are variable based on some other variable.
    Girdle thickness is the variable for table size and Tolkowsky did his calculations with no girdle (knife edge).
    For a 2% girdle he would have recomended 55.8%

    Just as he would have recomended a crown angle of 32.75 degrees for a pavilion angle of 41, had he had Jasper Paulsens computing power which you surely have used before here http://www.folds.net/diamond/software_help.html

    Tolkowsky Jasper 55.8% table.JPG
     
    


    


  16. strmrdr
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    by strmrdr » Jan 18, 2008
    1920s is when it took off. It wasnt really that common until the late 1930s and didnt hit some areas until after ww2.

    http://www.tvakids.com/electricity/history.htm
     
  17. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Jan 18, 2008
    John i did not entirely agree because diamonds are also enjoyed in daylingt.
    But please see Storm''s answer to when electric light came into force.
    It took 30 years to adjust the minor facets after lighting changed. Where was the science?
     
  18. strmrdr
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    by strmrdr » Jan 18, 2008
    getting smacked around by the establishment and laughed out of the room.
     
  19. JohnQuixote
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    by JohnQuixote » Jan 18, 2008
    You're certainly right about daylight Garry but diamonds are not sold there. I really think this adjustment was driven by feedback from merchants in the gradually evolving sales environment: In 1920 electric lights (low-hanging) started coming into use and sellers were just beginning to see the sizzle caused by adjustments. Jewelry store schemes evolved slowly and steadily. More powerful, multiple source spotlighting lent itself to lengthening of the lower halves but that did not happen overnight. Look at the complex schemes we have today. We're far from the first electric light schemes.

    Scientifically; Morse lengthened lower halves to about 60%, but Tolkowsky was the first to document that lower halves should have a specific relationship to the rest of the diamont (his were about the same as Morse's). Shipley indicated that they had lengthened to 75% in 1939, and since that time we've settled into a 75-85% range.

    So, from the introduction of electric lighting it's not surprising that it took some decades to get feedback upstream to the cutters (who were resistant as a habit anyway) about how they should cut to accomodate this new store-lighting idea...and then even more time and more adjustment as the store-lighting ideas themselves evolved. Strm makes a good point about the pushback all this "scientific cutting" received through the first decades of the 1900s.
     
  20. Rhino
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    by Rhino » Jan 18, 2008
    Good post Mike. I acquired a copy once it was released and am looking forward to sitting down with it as I finish up my current read. Al and I have discussed quite a few of the issues the last time I saw him in Vegas. Great stuff.


    I know quite a scores of consumers who would argue this point. As you know I feature a 10 fold type (Solasfera) and we have many extremely happy clients who visually preferred these over 8 fold symmetry who would say you''re wrong. I would say matter of preference really. Eye of the beholder.
     
  21. Garry H (Cut Nut)
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    by Garry H (Cut Nut) » Jan 18, 2008
    Good arguements John
    But I am not totally convinced - if the science was really valued, and it really was science, then as GIA Cut Team have said before, the minor facets should be important. Today it is rare to find a stone in the low 70''s or high 80%''s. It seems to have evolved that way beginning in the mid 1930''s and perhaps over shooting in the late 1960''s from my experiential observations (looking at clients diamonds and guessing the date of grannies engagement etc).
    I think it was cutters themselves.
    I have yet to hear any evidence that scientists or gemologists or even gemmologists were involved. (But i am only 1/2 way thru Al''s book).

    Jonathon pereferences are preferences. In your experiance would more people prefer under 1/2ct 10 fold stones or would a larger number of the preferences be in larger stones?
     
  22. Rhino
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    by Rhino » Jan 18, 2008
    Yep. Not the first 41.2 I''ve seen get "0". I''ve seen and had these in my hands. I can tell you ... not all AGS Ideals look the same.

    Recently I had in my hands two GIA Ex''s that made for an interesting study. Both with 34.5 crown angles and 41.0 pavilion angles, 55 tables and both with normal girdle cutting. One had "0" light performance while the other got a "3" which after a careful examination was based primarily on wonky optical symmetry resulting from funky azimuth angles on the lower girdles and variances in the angles causing leakage under the table resulting in the "3". Proof positive that slope angles don''t always tell the whole story in a critical exam at least.

    Also ... good points before strm especially with regards to Asscher''s and reflectors. I''ve been seeing some with what I might call "organized or patterned leakage" that can actually provide for an attractive pattern of contrast as long as it doesn''t extend over a broad range under the pavilion. It''s funny because leakage generally carries a negative stigma to it and indeed can cause that unattractive ring of death under the tables of rounds. However in certain fancy shapes patterned leakage can contribute to beautiful contrast when observed in diffuse light.

    It''s one reason why ray tracing results via a reflector image or even an accurate model isn''t necessarily the best tool for determing "beauty". If leakage contributes to contrast in a positive way, then a system that gives diamonds a hit for leakage may not be the best idea when attempting to judge diamond beauty in certain fancies. Food for thought.
     
  23. Rhino
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    by Rhino » Jan 18, 2008
    Since the demands I get are generally more for the .7xct and higher ranges I''m generally seeing and stocking more in these sizes (upwards to 2ct) but have sold quite a few in the 1/2ct range to folks who preferred them. I would however say that more people, in the smaller sizes prefer the 57 facet ex/id''s but I''ll never assume to predict what any person will prefer. I''ve even helped folks who truly preferred the appearance of a beautiful 10 fold but becuase others didn''t prefer it for one reason or another are talked out of it. [​IMG] My counsel is get what pleases your eyes and don''t worry about the rest of the world.

    I show them all and let them decide. I find a lot of the younger generations find the modfied rounds very appealing. Yesterday I helped a couple ... 19 year old girl and 22 year old guy who both preferred an 81 facet over 57, 91 and 129 who were looking at 1ct sizes. Everyone''s different. Can''t always predict what they will perceive as best.

    Peace,
     
  24. diagem
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    by diagem » Jan 18, 2008
    Strmrdr..., where is the + in a 10 fold vs. 8 fold when it comes to yields?
     
  25. diagem
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    by diagem » Jan 18, 2008
    I agree 100%..., All polished Diamonds have leakage..., round or fancies!
    In step-cuts the contrast they develop is translated into beauty when well cut.
    Every other fancy shape converts certain leakage into beauty as well.


    In rounds the attempt to minimize leakage is key for a good cut grade (as to my understanding at least...).
    But when tilted..., there is no running away from it...

    See image from Michael''s post on top:

    MCideall.JPG
     
  26. strmrdr
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    by strmrdr » Jan 18, 2008
    Im not sure why 10 fold allows steeper pavilion angles.
    The increased yeild is from the shallow crowns and deeper pavilions.
    This allows 2 heavier stones too be cut from the same rough.
    33/41.4 vs 34.8/40.8 with the same table size.
     
  27. diagem
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    by diagem » Jan 18, 2008
    In regards to future lighting changes..., I would imagine there some issues about it... (but dont think it will become a huge one!!)
    But since Diamonds are enjoyed today in many lighting environments..., I assume it should no longer be a huge issue as it was in the transferring from candle-light to electric light!

    I for example check/study on a regular basis the Diamonds I design and cut in as many lighting environments as I can..., both during and after completion of the cutting process!
    I assume a lot of cutters practice these issues today!

    On the other hand..., stores use lighting tricks to show their jewelry as best..., but it seems the consumers are getting more educated not only in the Diamond cuts...., but also in the fact which I hear a lot of them (consumers) request to view the Diamonds they contemplate purchasing in as many lighting environments as due possible in the store...., I hear a lot of consumers expect to view the Diamonds in outside light which sometimes puts the jewelry store in an uncomfortable situations!

    Just my thoughts on this issue..., but may be completely wrong!
     
  28. strmrdr
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    by strmrdr » Jan 18, 2008
    Check this thread please :}
    https://www.pricescope.com/community/threads/mandated-cft-and-the-diamond-cut.76655/
     
  29. diagem
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    by diagem » Jan 18, 2008
    Strmrdr,

    If the above examples had the same girdles, depth and diameter..., which one would weigh more?
    The shallow or deep crowned one?
     
  30. strmrdr
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    by strmrdr » Jan 18, 2008
    I can get you that answer tomorrow but shallower crowns will yield 2 heavier stones from the same octahedron rough compared too higher crowns.
     
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