Confused...

[ejh]

Ok, so I have figured out how important cut is when choosing a diamond, but I am a little confused with the "ideal" grade.

I definitely want an AGS 000 ideal cut, but is the "Hearts and Arrows" cut even higher? Where does "A Cut Above" fit in...?

I also know that I want to get a diamond with an HCA score below 2, but once you are below 2, is there a significant difference in performance?

Could someone help me out a little?

Thanks!

 

[starryeyed]

HI EJH and welcome to Pricescope forums!

I am not an expert, but I'll try to give a quick-and-dirty explanation. AGS Ideal cut stones cover a range of cut proportions. GIA Excellent cuts also cover a range, some of which intersect with the AGS Ideal cuts, some do not. GIA just started giving cut grades in 2006. Their cut scale has fewer classes than AGS. Hearts-and-Arrows and A-Cut-Above further narrow the field of Ideal Cut stones.

A H&A stone will display perfect arrows face-up, and perfect hearts face-down. Many stones may look like they display hearts and arrows, but there may be something slightly off so that the hearts/arrows aren't perfect. It's a fairly tight range of proportions. ACA is similar. Whiteflash explains the range of proportions that qualify for ACA on their website.

HCA is light performance based. With the little experience I have, I've seen some non-ACA stones perform better on HCA than other ACA stones. The HCA is meant as a guide to help you distinguish which stones are better performers.

So I think it comes down to your cut sensitivity. I'd be perfectly happy with an Ideal (AGS) or Excellent (GIA) stone that wasn't a H&A exactly, but had Excellent light performance (2 or less). Some folks are enamored with H&A and ACA and wouldn't buy anything else.

Perhaps one of the experts will chime in and give you a more scientific answer, but in the meantime, I hope this helps.

 

[belle]

that''s a pretty good summary starryeyed

i just see one aspect that needs to be clarified:

Date: 11/30/2006 11:34:54 AM
Author: starryeyed

HCA is light performance based. With the little experience I have, I''ve seen some non-ACA stones perform better on HCA than other ACA stones. The HCA is meant as a guide to help you distinguish which stones are better performers.

hca is not ''light performance based''. hca gives a ''score'' based on angle combinations. it can help you find combinations that are known to perform well together but it is no guarantee of ''light performance''. there are too many unknowns within each diamond for a tool that never sees or touches the diamond to be able to determine performance. it''s primary use is to weed out angle combinations that do not work well, not pick one diamond over another.
hope that helps some!

 

[starryeyed]

Thanks for clarifying Belle. I think I may have used the wrong choice of words. I guess what I intended to say is that the HCA, as I understand it, attempts to predict how a diamond may perform with respect to certain light performance metrics, i.e. - Light Return, Fire, Scintillation, and Spread. The algorithm is much more complex than just the set range of proportions. Like an ACA stone may fall within a certain range of proportions, but that designation doesn''t say much about how well the diamond might perform with resepct to LR, F, Sc and Sp. The HCA can help estimate this "performance", for lack of a better word.

I think you brought up an important point Belle about the unknowns. If the symmetry is off or the girdle falls outside of the assumed range, etc., the HCA results may not actually describe how the stone performs in reality. EJH, I think this is where some of the "Ideal" proportion ranges come in handy.

I hope this is clearer. Sorry for any confusion, especially considering you''re already "Confused..."