Find your diamond
Find your jewelry
shape
carat
color
clarity

AGA/pavilion angle

Status
Not open for further replies. Please create a new topic or request for this thread to be opened.

mrmarius

Rough_Rock
Joined
Sep 15, 2002
Messages
63
I was reading CutNut's article on this site about the HCA and especially was intriqued by the page talking about how the worst performing proportions in the top grades for various grading systems score on the HCA. Very enlightening. (pardon the pun). :))

I noticed that one of the columns in the chart was pavilion angle and that the AGA system was in the chart. But I don't see pavilion angle on the AGA cut charts on this site. Is pavilion angle part of the way an AGA cert is arrived at? Or do other measurements of the stone 'force' the pavilion angle into a certain range?

Thanks,
Marius
:wavey:
 

oldminer

Ideal_Rock
Trade
Joined
Sep 3, 2000
Messages
6,394
When we created the AGA charts I used to measure every stone manually. It was easier to be accurate with percentages instead of angles. Yes, the angles are determined by the percentages anyway. There is a direct trigonometric relationship.

Now, angles are all the rage. We have sophisticated equipment to measure them directly. It does not make any difference, but angles are more "in"...There is no actual difference of grand importance.

The difference lies in culet size. The larger the culet the larger the angle at any given percentage depth. The whole culet thing is so minor, but it is why there can be some differences. My tables are based on small to no culet size.
 

mrmarius

Rough_Rock
Joined
Sep 15, 2002
Messages
63
Thanks for the explanation. It makes sense, what you said about culet size. I can see in my mind the angle getting larger as the culet increases.

To an ex-math-major geek like myself, this stuff is fascinating. I should get engaged more often.
 
Status
Not open for further replies. Please create a new topic or request for this thread to be opened.
Be a part of the community It's free, join today!
    Recutting And Resetting A Heirloom
    Recutting And Resetting A Heirloom
    Princess Diana: Timeless Jewelry Every Woman Should Own
    Princess Diana: Timeless Jewelry Every Woman Should Own
    Diamond Jewelry For 4th Of July Quarantine Celebrations
    Diamond Jewelry For 4th Of July Quarantine Celebrations

Need Something Special?

Get a quote from multiple trusted and vetted jewelers.

Holloway Cut Advisor



Diamond Eye Candy

Click to view full-size image.
Top