HCA results are for Medium Girdle?

[gr8foolishness]

How much do the HCA results vary based on a thin or thick girdle? And what range of measurements constitutes thin/medium/thick based on the measurements given on a Sarin report or AGS certificate-these measurements are from valley to valley-correct?

 

[Garry H (Cut Nut)]

Girdle has a very minor effect on beauty and a major effect on spread. The latter is taken into account a little - we will have a fee based service soon that does more with girdle.
Thicker girdles can sometimes improve diamond beauty and sometimes reduce it - it is non obvious.

 

[gr8foolishness]

Thanks for your reply-although I still have a couple of questions. I read your tutorial on spread, I understand the concept, but how is it calculated? And what measurement constitutes a thin, medium, and thick girdle-and is that measurement from valley to valley or the thinnest and thickest part of the girdle?

 

[Garry H (Cut Nut)]

thin bit to thin bit
different labs use different methods
Marty haske has a site that shows it all
it is more complex than you probably need to know about
medium to slightly thick is all you really need to know I think

 

[pricescope]

[/u]

 

[gr8foolishness]

Thanks again-so it seems that the GIA says girdle thickness is relative to the size of the stone-yet then there is actually a constant and you can do the math and figure out whether the girdle is thin, medium, thick-my main question is the math-the girdle number on a Sarin report is listed as a % of the diameter of the diamond? If I take the girdle measurement of 1.4% on a diamond that is 5.71mm in diameter, the girdle would be .07994mm-this doesn't make sense with the graphs in the article-what am I doing wrong? Help!

 

[Garry H (Cut Nut)]

Gr8 are you buying certified diamonds or about to start your own lab?
These decisions are made differently by different labs with different rules etc.
I think you should communicaate directly with the labs because I may well wrongly advise you on such very specific questions.
if your questions concern the purchase of a diamond then I really feel you are in way to deep in your line of enquiry. If that is the case then you are possibly going to end up buying an 8* and you will be devastated when you see the girdle.
Garry

 

[gr8foolishness]

Maybe I am not phrasing my question correctly-what constitues a medium girdle-i.e.since you can't use %'s to determine a girdle rating(thin,medium,thick)is there a range of measurement .5mm, 1mm, 1.5mm, etc. that would be medium?