HCA - what is the cut off point

[spike13]

When using the HCA as a guide, what is the general cut off point if you want a real fire cracker?

I''ve been limiting my search to 1 or better -- am I being too strict?

thanks in advance!

 

[strmrdr]

under 1 may be worse in a ring than a 1.9
Under 2 and sometimes slightly over for specific combos, then its time too move on too IS or ASET images and a contrast evaluation for ones with pavilions 40.5 and under unless they have a crown angle 35+ and a small table.
40.6 can sometimes have issues if most of the facets are under it but its less common.
An in person eval of the diamond by a trusted expert vendor can weed out such stones.

Read this please it will help answer your question:
http://diamonds.pricescope.com/ideal.asp

 

[jewelrychic1]

I read the article, but don''t understand why this is such crucial information. Can you explain to me?

 

[spike13]

Date: 4/11/2008 10:16:19 PM
Author: strmrdr

Read this please it will help answer your question:

http://diamonds.pricescope.com/ideal.asp

I did read this LOL -- but I still wasn''t quite sure how to interpret the number. I guess it''s very tempting to simplify with lower is always better.

I''m going to go with Whiteflash or GOG because of their reputation here. Do folks usually just trust their opinions or do they have multiple stones sent for in person evaluation?

 

[Garry H (Cut Nut)]

For a ring in a diamond with super symmetry I thnk you could go to 2.5. Especially if the stone is painted a little - but you need to see idealscope images to be sure of that level of detail

 

[diamondseeker2006]

Date: 4/11/2008 10:49:45 PM
Author: spike13

Date: 4/11/2008 10:16:19 PM
Author: strmrdr

Read this please it will help answer your question:

http://diamonds.pricescope.com/ideal.asp

I did read this LOL -- but I still wasn''t quite sure how to interpret the number. I guess it''s very tempting to simplify with lower is always better.

I''m going to go with Whiteflash or GOG because of their reputation here. Do folks usually just trust their opinions or do they have multiple stones sent for in person evaluation?

Once you are at 2.0 and under, lower is not better. Many people aim for between 1 and 2 because of what Storm said above. And Garry said you can sometimes go up to 2.5.

WF ACA''s are top cut quality and you don''t even need to put the numbers in the HCA. You might want to do that on the Expert Selection stones. If Good Old Gold calls a stone hearts and arrows, then it is usually an excellent cut and you also wouldn''t need to use the HCA. I have bought from both GOG amd WF, and I was able to choose the stones from the info on the websites.

You might want to try to stay close to these parameters:

table 54-57

depth 60-62

crown angle 34-35

pavilion angle 40.6 - 41.0

girdle thin, medium, slightly thick

 

[Lorelei]

HCA should not be used to select diamonds, it is an elimination tool. You select diamonds with Idealscope, and your vendor's help, and ultimately your own eyes.

If you are looking at well cut in house diamonds, then use Idealscopes or limit your search to AGS0 and GIA Excellent to make finding a well cut diamond easier.

I would add to the numbers DS listed above, that if you find a diamond which is perhaps a touch deeper, then that should not be a problem if everything else is right ( i.e. up to 62.4% for example, but it is a preference thing). And also evaluate carefully diamonds with crown and pavilion angles towards the shallower ends 34/ 40.6 and steeper 35/ 41 to make sure they work well with that particular diamond. Idealscope is useful for this. Lastly, if a trusted vendor advises you that a diamond is fabulous and the IS and everything else confirms it, but the numbers are slightly out of the suggested range, then of course consider it.

 

[arjunajane]

Spike,
I totally agree with Lorelei here - I think the HCA is useful if you know what you''re looking for and want to weed out a number of stones from a pool.
Otherwise, you''re choices should really be selected using IS images and the opinions of your trusted rep. And yes, most people here tend to trust the expert opinion of WF or GOG - they are well known for being honest with you about how eyeclean a stone is, etc.
The key is to really explain your priorities to your vendor - maybe put it in an email so they can refer back while looking around for you? Make sure you explain what you''re personal definition of "eyeclean" is, and how comfortable you are with lower colour grades etc.
GOG in particular has Everything you need to evaluate a stones merits already loaded on their site - IS images, H&A views, BScope etc etc. If its not there, jus email and their lab tech will get it done quicksmart. Only thing to do is pick a couple out and ask Jon whcih is the best choice!

I guess what I''m trying to say is, let your eyes be the judge, use the HCA to Eliminate stones, not choose them.
Hope that helps some.