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# Convert percentages to angles???

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#### hunter3316

##### Rough_Rock
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%

#### pricescope

##### Ideal_Rock
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

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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
----------------
... but what does ATAN stand for?
Mike
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Mike, ATAN (Arctangent) is reciprocal to TAN (Tangent)

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

#### hunter3316

##### Rough_Rock
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
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
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
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

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