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Crown and pavilion calculation

P: 11/10/2004 10:14:25 PM
PunchNPie75 Ideal Rock Total Posts: 1,227 Last Post: 2/9/2008 Member Since: 8/5/2004	hi! this is a longshot but... is there any way to figure out the crown and pavilion angles of a stone without the sarin analysis? i got my stone before we found this site and learned about all this. My stone is GIA, so i dont have any of that info, only table,depth, etc. my stone is beautiful but i'm always curious what these numbers are since everyone here says they are the most critical in determining how ideal the cut is thanks My favorite color is sparkle!!!
Posted: 11/10/2004 10:14:25 PM

There are 9 replies to this message. There are 9 replies on this page.

P: 11/10/2004 11:21:16 PM
Garry H (Cut Nut) Ideal Rock Total Posts: 11,579 Last Post: 11/23/2009 Member Since: 8/16/2000	Not once it is set and not without a sarin scan But you can examine it with an ideal-scope which will tell you more than the scan info anyway Garry Holloway FGAA DipDT HCA and Ideal-scope developer http://www.ideal-scope.com and http://www.HollowayDiamonds.com.au
Posted: 11/10/2004 11:21:16 PM

P: 11/11/2004 12:09:06 AM
diamond island Rough Rock Total Posts: 78 Last Post: 7/28/2005 Member Since: 6/17/2004	Is the ideal scope the same or similar or gives you the same information as the Firescope used to sell the eightstar?
Posted: 11/11/2004 12:09:06 AM

P: 11/11/2004 1:48:24 AM
Garry H (Cut Nut) Ideal Rock Total Posts: 11,579 Last Post: 11/23/2009 Member Since: 8/16/2000	Yes. I have had a Firescope for 20 years. Garry Holloway FGAA DipDT HCA and Ideal-scope developer http://www.ideal-scope.com and http://www.HollowayDiamonds.com.au
Posted: 11/11/2004 1:48:24 AM

P: 11/11/2004 7:10:03 AM
asblackrock Cut Rock Total Posts: 201 Last Post: 12/11/2005 Member Since: 10/16/2004	For round brilliant cut diamonds I have worked out a formula for calculating crown and pav angles if you have crown height and pav depth (see: An easy way of calculating crown and pavilion angles ). The only problem is that figures for crown height and pav depth are apparently rounded off to the nearest whole number, so results are only approximate. A GIA certificate will unfortunately not give you any of this info though. PS The name glaucomflecken caught my attention. Is there an optometric/ophthalmological connection? Angela
Posted: 11/11/2004 7:10:03 AM

P: 11/11/2004 8:17:34 AM
Nicrez Ideal Rock Total Posts: 3,230 Last Post: 10/21/2009 Member Since: 1/21/2004	There are actually methods that can help you determine the angles, or approximate them. There is a semi-mathematical way to determine it, but to do so would be a bit complex, and I would have to explain some ways of finding OTHER information about your stone first. When i get a chance, I will try to post the method later... You could always take it to a gemologist, and they could literally eyeball it and let you know the approximations in a few minutes. "Sometimes it's OK to throw rocks at girls...as long as they sparkle! " Nicrez, G.G., A.J.P.
Posted: 11/11/2004 8:17:34 AM

P: 11/11/2004 9:30:47 AM
PunchNPie75 Ideal Rock Total Posts: 1,227 Last Post: 2/9/2008 Member Since: 8/5/2004	Thanks everyone. My stone is really sparkly so I will assume those proportions are ideal :) Angela: You are correct, I am an optometrist. my friends and i in school thought glaucomflecken was a fun word to say (although a serious eye condition). i'm a nerd. My favorite color is sparkle!!!
Posted: 11/11/2004 9:30:47 AM

P: 11/11/2004 8:02:29 PM
Garry H (Cut Nut) Ideal Rock Total Posts: 11,579 Last Post: 11/23/2009 Member Since: 8/16/2000	Date: 11/11/2004 8:17:34 AM Author: Nicrez There are actually methods that can help you determine the angles, or approximate them.  There is a semi-mathematical way to determine it, but to do so would be a bit complex, and I would have to explain some ways of finding OTHER information about your stone first.  When i get a chance, I will try to post the method later... You could always take it to a gemologist, and they could literally eyeball it and let you know the approximations in a few minutes. Nicrez you may have learned, or will be taught the Liddicaot Rapid Sight Pavilion Depth Estimation method. I am afraid to tell you, it has errors and should not be used. In your library your GIA library can get http://www.austgem.gil.com.au/ab21-10.html and learn about it. I doubt your lecturers will want to know about it though. The rapid sight system is what led the industry to use pavilion depth % as a measure of cut quality. This is a great pity because people assume a correlation between pavilion depth and pavilion angle. They almost always get a lower angle than it actually is, and this is very bad because as we know the difference between 40.9 and 41.1 is rather large in cut quality. So Angela, I strongly advise you do not propagate the math method because depth % is almost always understated by scanners. Garry Holloway FGAA DipDT HCA and Ideal-scope developer http://www.ideal-scope.com and http://www.HollowayDiamonds.com.au
Posted: 11/11/2004 8:02:29 PM

P: 11/11/2004 8:12:35 PM
JohnQuixote Ideal Rock Total Posts: 5,212 Last Post: 5/24/2008 Member Since: 9/9/2004	Date: 11/11/2004 2:29 PM Author: Garry H (Cut Nut) Nicrez you may have learned, or will be taught the Liddicaot Rapid Sight Pavilion Depth Estimation method. (Aside: I'll bet we never expected to see that and "glaucomflecken" in the same thread...) John __________________________ John Pollard Whiteflash Director of Education 2004-2007
Posted: 11/11/2004 8:12:35 PM

P: 11/11/2004 8:41:53 PM
PunchNPie75 Ideal Rock Total Posts: 1,227 Last Post: 2/9/2008 Member Since: 8/5/2004	Date: 11/11/2004 8:12:35 PM Author: JohnQuixote Date: 11/11/2004 2:29 PM Author: Garry H (Cut Nut) Nicrez you may have learned, or will be taught the Liddicaot Rapid Sight Pavilion Depth Estimation method. (Aside: I'll bet we never expected to see that and 'glaucomflecken' in the same thread...) My favorite color is sparkle!!!
Posted: 11/11/2004 8:41:53 PM

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