Can someone take a look at GIA and guess crown height?

[amyholder]

I was just reading another thread that said you can "guesstimate" crown height by the GIA certificate. I looked at mine, and can''t for the life of me see how to. Does anyone mind taking a look at the cert? Thanks so so so much!

GIA Certificate #
2111123895
Carat Weight- 1.15

 

[Circe]

I have no idea how to use the GIA cert, but if you tell me the crown angle and the table percentage, I can tell you what the crown height should be ... there''s a table.

(Alternately, just tell me how to access the GIA cert!)

 

[Fly Girl]

Date: 11/28/2009 8:21:36 PM
Author: Circe
I have no idea how to use the GIA cert, but if you tell me the crown angle and the table percentage, I can tell you what the crown height should be ... there''s a table.

(Alternately, just tell me how to access the GIA cert!)

GIA Report Check Link

 

[whatmeworry]

Okay so take a ruler and measure the green line (crown height) in the picture below. Then divide that by length of the red line (diameter). Then multiply by 100. That should give you the crown height %.

 

[Circe]

Thanks, Flygirl! That is one nifty system ....

That said, dagnabbit! My chart only works for rounds, and the formula that WMW (nice, btw!) lists requires information that isn''t listed. Wish I could have been more help ....

 

[FB.]

Date: 11/28/2009 8:41:04 PM
Author: whatmeworry
Okay so take a ruler and measure the green line (crown height) in the picture below. Then divide that by length of the red line (diameter). Then multiply by 100. That should give you the crown height %.

Agreed. That's a screening methond that I use for non-round stones.
GIA certs usually show the stone's profile to scale, even though it has a disclaimer below. So it is possible to get a rough idea of the crown height.
But take care not to place too much emphasis on an estimate done with a basic school ruler, since a small error in your measurement (or a small error on GIA's profile) could get amplified into a much larger error. See what happens when you add or take a couple of % from your approximation, to see how a small measurement error might affect your interpretation of cut quality.