Find your diamond
Find your jewelry
shape
carat
color
clarity

Convert percentages to angles???

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

hunter3316

Rough_Rock
Joined
Apr 1, 2003
Messages
30
Can anyone tell me how to convert crown and pav. percentages to angles... assuming no cullet.

I want to do it for these two diamonds:

1:
Depth:61.3%
Table; 56%
Crown: 14%
Pavilian: 43%

2:
Depth:59.9%
Table;58%
Crown:14%
Pavilian:43%

thanks for your great help!!!!
 

pricescope

Ideal_Rock
Joined
Dec 31, 1999
Messages
8,266
Did you get the data from EGL report? If they are rounded there will be rather high error in HCA.

You can use these formulas to convert % to angles without culet:

CrownAngle = ATAN (2 * CrownDepth% / (100 - TableSize))
PavilionAngle = ATAN (PavilionDepth% / 50)
 

MikeC

Rough_Rock
Joined
Apr 3, 2003
Messages
17

----------------
On 4/24/2003 5:32
2 PM leonid wrote:
Did you get the data from EGL report? If they are rounded there will be rather high error in HCA.

You can use these formulas to convert % to angles without culet:

CrownAngle = ATAN (2 * CrownDepth% / (100 - TableSize))
PavilionAngle = ATAN (PavilionDepth% / 50)----------------
I was wondering how to do this as well.

leonid,
Thanks for the equation, but what does ATAN stand for?
Mike
 

pricescope

Ideal_Rock
Joined
Dec 31, 1999
Messages
8,266
----------------
... but what does ATAN stand for?
Mike
----------------
Mike, ATAN (Arctangent) is reciprocal to TAN (Tangent)

On Windows' Calculator (Scientific Mode) select INV and hit TAN.
 

hunter3316

Rough_Rock
Joined
Apr 1, 2003
Messages
30
Thanks, thats exactly what I was lookin for.

To answer your question YES, these numbers are from EGL. How much of an eror could I expect, according HIC scoring. I supose theres no other way to fix this except to do the SERIN hu? Also whats the average error for converting EGL %'s to HIC scores?

Thanks!
 

MikeC

Rough_Rock
Joined
Apr 3, 2003
Messages
17
Thanks leonid. Originally I just had the pav. percentage and got a score of 1 on the HCA but was not to sure how reliable that was because it was a percentage and not an angle. After doing the conversion my score actually went down to .9. That made my day
 

pricescope

Ideal_Rock
Joined
Dec 31, 1999
Messages
8,266
hunter3316:
----------------
I supose theres no other way to fix this except to do the SERIN hu?
----------------
Correct...
----------------
Also whats the average error for converting EGL %'s to HIC scores?
----------------
It depends on particular values. I just tried to plug pavilion depth of 43.0% and 43.5%. In both cases I've got HCA < 2 which is pretty good.

However, there will be more dramatic difference once you go closer to 43.8%-44.0% pavilion depth since diamond will leak more light under the table.
 

pricescope

Ideal_Rock
Joined
Dec 31, 1999
Messages
8,266
Mike, actually when one enters pavilion or crown depth %, HCA converts it into angles anyway because HCA is based on angles.

We believe Sarin angle data are more accurate than depth% because later depends on accuracy of girdle and culet measurements.

Still, even angles data have certain error so don't fight for each tenth of HCA score
 
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!
    Horses for Courses: Polo Match Jewelry
    Horses for Courses: Polo Match Jewelry
    An Excellent K Color Graded Diamond
    An Excellent K Color Graded Diamond
    Astounding AVR
    Astounding AVR

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