Got Diamond Questions?
Our community of diamond experts are here to provide answers
SweetGwendolyn

Could G.I.A. make an error in the depth percentage on a certificate?

Recommended Posts

For example G.I.A. Certificate 6197179944

11.10 x 11.15 x 6.72

11.10+11.15=22.25/2=11.125=11.13

6.72/11.13=0.60377358=60.37=60.4 total depth.

It states 60.3 depth, should it say 60.4? Does G.I.A. round up in their calculations?

Edited by SweetGwendolyn

Share this post


Link to post
Share on other sites

The GIA figures the depth % as the depth/ the average diameter. 

 

 

Edited by LaurentGeorge

Laurent George
Diamond Ideals
New York City

www.diamondideals.com
212-207-4845
laurent@diamondideals.com

 

 

Share this post


Link to post
Share on other sites

On round brilliants they calculate depth percentage using the average diameter, as you have done, but I think they're truncating that 4th significant digit at the end, not rounding it. (60.37 ends up 60.3, not 60.4)  


Neil Beaty

GG(GIA) ICGA(AGS) NAJA

 

There's never a crowd when you go that extra mile.

Professional Appraisals in Denver

Share this post


Link to post
Share on other sites

Neil,

So 60.37 equal to 60.3 because G.I.A. does not round the number? But in mathematics, it would be right. Just think that odd not to round it.

Edited by SweetGwendolyn

Share this post


Link to post
Share on other sites

I have actually just tested the various scenarios and found a number of inconsistencies but for the most part, Neil's explanation works. 


Laurent George
Diamond Ideals
New York City

www.diamondideals.com
212-207-4845
laurent@diamondideals.com

 

 

Share this post


Link to post
Share on other sites
2 hours ago, SweetGwendolyn said:

Neil,

So 60.37 equal to 60.3 because G.I.A. does not round the number? But in mathematics, it would be right. Just think that odd not round it.

It’s not as peculiar as it sounds. The same thing happens, for example, with weights.  0.919 equals 0.91, not 0.92.  Most calculators do this too.  If you've got 8 digits, the 9th isn't rounded, it's truncated. 

It doesn't affect the conclusion in this case but 11.125=11.12, not 11.13, for the same reason. 

Edited by denverappraiser

Neil Beaty

GG(GIA) ICGA(AGS) NAJA

 

There's never a crowd when you go that extra mile.

Professional Appraisals in Denver

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now