A perplexing H&A diamond?!? Is it or is it not? Experts, pls advice

[jdn1976]

Hi all,

First off, I want to say what a great website this is for newbies like me! I''ve been lurking in this forum for a few weeks now, gathering information and confidence to make an e-ring purchase. I''m looking to get a H&A round brilliant diamond and I think I found one that meets my specs with the following dimensions:

Carat: 0.6
Cert: GIA
Measurements : 5.45 - 5.49 x 3.33
Depth : 60.9
Table : 55%
Girdle : Medium, faceted
Culet : None
Polish : Excellent
Symmetry : Excellent

The vendor provided me the attached mega-scope report (below). After I keyed in the crown, pavilion and cutlet angles (their average angles), it returns a HCA score of 1.4. However, I "studied" the angles of the individual facets and it seems to me that they vary considerably, even the table proportions, the only constant is the depth and cutlet.

My questions are:
1) Can we calculate the HCA for each "side" by keying in the angles for that "side"? Example for "Side 1", table = 54.5%, crown = 34.5 deg, pavillion = 40.8 deg? I did just that and the most of the sides came out with HCA scores under 2. Only for "Side 7", did the HCA return a score of 3.2

2) I thought that H&A diamonds were supposed to be symmetrical (especially one that GIA has graded with excellent symmetry), should the angles vary so much?

3) Would this diamond qualify for an AGS000?

4) Basically, what does everyone think of this diamond? (You can see the brilliancescope results, lightscope and H&A pics).

I want to say a big thank you in advance to all who took the time to respond to my post!

 

[jdn1976]

Brilliancescope

 

[jdn1976]

Lightscope...

 

[jdn1976]

H&A

 

[JohnQuixote]

Date: 1/22/2005 5:26:58 PM
Author:jdn1976


Hi all,

First off, I want to say what a great website this is for newbies like me! I've been lurking in this forum for a few weeks now, gathering information and confidence to make an e-ring purchase. I'm looking to get a H&A round brilliant diamond and I think I found one that meets my specs with the following dimensions:

Carat: 0.6
Cert: GIA
Measurements : 5.45 - 5.49 x 3.33
Depth : 60.9
Table : 55%
Girdle : Medium, faceted
Culet : None
Polish : Excellent
Symmetry : Excellent



The vendor provided me the attached mega-scope report (below). After I keyed in the crown, pavilion and cutlet angles (their average angles), it returns a HCA score of 1.4. However, I 'studied' the angles of the individual facets and it seems to me that they vary considerably, even the table proportions, the only constant is the depth and cutlet.

My questions are:
1) Can we calculate the HCA for each 'side' by keying in the angles for that 'side'? Example for 'Side 1', table = 54.5%, crown = 34.5 deg, pavillion = 40.8 deg? I did just that and the most of the sides came out with HCA scores under 2. Only for 'Side 7', did the HCA return a score of 3.2

No, the diamond’s score is 1.4… HCA works on the given averages for a reason. More below.

2) I thought that H&A diamonds were supposed to be symmetrical (especially one that GIA has graded with excellent symmetry), should the angles vary so much?

Your questions on the symmetry are very logical. What you need to know is that HCA is based on the averages of the angles for a reason… As long as the opposites average without extreme variance the light performance will be that of the given angle.

Read this description of symmetry which will give you insight (physical symmetry section) on why this works.

Now... For this stone here are your crown opposites (34.3 given angle)

34.4 / 34.4 (34.4 avg)
34.5 / 34.3 (34.4 avg)
34.5 / 34.1 (34.3 avg)
34.3 / 34.6 (34.45 avg)

Here are your pavilion opposites (40.9 given angle)

40.8 / 41.2 (41.0 avg)
40.7 / 40.9 (40.8 avg)
40.8 / 40.8 (40.8 avg)
40.9 / 40.8 (40.85 avg)

The crown averages vary by only 0.15 and the pavilion averages vary by only 0.20. This is extremely tight. You have no worries.

3) Would this diamond qualify for an AGS000?

Yes. And with proven proportions.

4) Basically, what does everyone think of this diamond? (You can see the brilliancescope results, lightscope and H&A pics).




I want to say a big thank you in advance to all who took the time to respond to my post!

In case you can't tell I think it's a great stone. Light leakage is almost nil and the H&A pattern is good. It will be better than most diamonds you will ever see and should perform in a broad range of lighting conditions.

 

[Lynn B]

Can't add a thing to John's expert opinions, except... wow, looks like a KILLER STONE to me!!!!

Lynn

 

[perry]

jdn:

Welcome to pricescope.

I am not an expert on all the angles and AGS ratings, but I can provide some "general" information.

First, that diamond will almost certainly look very good to you and anyone else. Based on what I know - top 1% or less of diamonds have that good of idealscope image.

HCA is a guide, not an exact science. There are tradeoffs in it to produce its composit score. The purpose of the tool is to allow you, or I, to sort out the diamonds that we probably should not waste out time looking at - if we want a great light return diamond (one with life in it). It is not perfect in this. I am told that there are some great looking diamonds that will have HCA greater than 2. Once you get below 2 the HCA does not really tell you much. A diamond with an HCA of 1.9 may look better than a diamond with an HCA of 0.5. All it does is get you into a known bunch of great looking diamonds for you to perform final selection from. Analyzing individual pairs of facets will not affect these results, nor alter the look of the diamond.

The Brilliantscope is an interesting tool, and you have a graet looking diamond from that perspective as well. However, it too is a limited tool. My take on it (and you will hear other views) is that imagine there is a small pool of great looking diamonds, and an ocean of not so great looking and outright dead diamonds. If you analyze all of these diamonds with the Brilliantscope you will find that it will produce poor reports for the ocean of not so great and dead diamonds, and for a portion of the great looking diamonds. However, you will find that all diamonds with a great Brilliantscope reports come from the small pool of great looking diamonds. Stated another way, it can definitely tell you that your diamond is great looking. But it may not give a good report to other great looking dimonds. Hence, many in the diamond industry have mixed feelings on it as they have other great looking diamonds that do not get good brilliantscope reports.

Is it an H&A. Interesting question.... Hearts and Arrows represents a specific pattern and many vendors display "similar" patterns and call the H&A. I will note that it is my understanding - from very credible sources - that H&A was developed in Japan and that production was limited because of the time consuming process needed to meet the initial quality standards (the impression I get was that facets were controled to very tight tolerneces similar to the way that 8* controls theirs - just not to the same extreem, and that it there was not enough of a market for such a premium product). The same sources have told me that most (if not the vast majority) of diamonds currently marketed as H&A in the US do not meet the quality of cut and pattern standards of the original standard.

NiceIce also makes similar claims on their site. I also find it interesting that "Hearts on Fire" does not claim to be an H&A diamond - although the ones I looked at had the best H&A patterns that I have seen.

One thing you can look at is your "Hearts" picture and note the uniformity - or lack of - of the hearts and the spaces and other things. Your''s is not the most uniform I have seen.

Is it an H&A. Good question. It seems that there are varying degrees of H&A standards in US marketing (just as there seems to be a variation of "ideal" cut standards).

I will also note that the H&A pattern does not in itself make a great looking diamond. Most great looking diamonds do not show great H&A patterns (and you could have a great H&A pattern and have a dead stone for light return).

There is no such thing as a perfectly symetrical diamond and variablity in individual facets exist in every diamond. The labs have different standards as to what they consider excellent. GIA rates range of tolerence as excellent. Who are we to quibble on that.

Between an HCA of less than 2, a good IdealScope image, and a megascope report to verify the angles and tolerences, you have enough information to state that this should be a great looking diamond. The Brilliantscope report is just a bonus confirmation of it.

Perry

Perry

 

[jdn1976]

Hi all,

thanks for all the fast replies!

John:
Your explanation is very clear and I understood most of it but I was wondering whether there was a typo in your crown opposites analysis, one of my crown angles is 33.6 vs 34.3, which would give it an average of 33.95. In this case, this particular set seems to an outlier from the average?

So with one crown angle of 33.6, this would still qualify for AGS000? My understanding is that for AGS Ideal Cut Proportion, Crown Angles must fall between 33.7° - 35.8°, or do they also take the averages?

Btw, ACA diamonds look really great and the best thing is you have a number of similar sized diamonds so I hope to get a pair one day for a set of solitaire ear-rings!

Perry:
Thanks for driving some sense into me, I know that a lot of people, myself included can''t tell the difference. Its just the knowledge that you are going to use a diamond to propose to the ONE (together 7 years and counting

), you just can''t help but want it to be even better. I will probably never be contented with the diamond I buy for her (even though she will be) becos I know she deserves better.

 

[JohnQuixote]

Perry gets an A+ for HCA and B''Scope assessment.

I have some of my own perspective to share on his H&A comments.

Date: 1/22/2005 6:20:26 PM
Author: perry
The same sources have told me that most (if not the vast majority) of diamonds currently marketed as H&A in the US do not meet the quality of cut and pattern standards of the original standard.

This is a simplification. However, it''s a fact that there are many untrue (phony) and near-true H&A on the market which have diluted the standards of "true" patterning that some cutters, brands and vendors insist on to this day. The H&A pattern posted above is too small to make finite judgements, but going on what I can see it appears to be near-true and better than an abundance I see marketed. I consider myself a H&A purist, but also a realist.

One thing you can look at is your ''Hearts'' picture and note the uniformity - or lack of - of the hearts and the spaces and other things. Your''s is not the most uniform I have seen.

Is it an H&A. Good question. It seems that there are varying degrees of H&A standards in US marketing (just as there seems to be a variation of ''ideal'' cut standards).

Yes, there are varying standards. This link lists the criteria I believe constitutes extremely picky patterning. Perry, I''m not sure how many true H&A diamonds you''ve compared (visually and analytically) next to those with near-true patterning and equal measurements. I''d be interested in hearing what you''ve observed.

Between an HCA of less than 2, a good IdealScope image, and a megascope report to verify the angles and tolerences, you have enough information to state that this should be a great looking diamond. The Brilliantscope report is just a bonus confirmation of it.

Perry

Perry

I wholeheartedly agree. This is a dynamite diamond.

 

[JohnQuixote]

JDN - You have the right of it. 33.95 (that's what I get for not double-checking). That still puts the averages within .5 of a degree. Even if that pinged the radar I'd just check the IdealScope (LightScope) image. The average - what is on the grading report - determines the Ideal status.

Remember that the ultimate test will be when you see it live (assuming you have not).

Thanks for the comments about the ACAs. Brian is very dedicated. By the way, I like the "I will never be contented because I know she deserves better" sentiment. Very nice.

 

[perry]

John:

All of those jewelry stores I visit that are selling "H&A" diamonds and love showing off their H&A patterns.... Are you implying that those arn''t "true" H&A. Those jewelers think so....

What was really interesting was that the Hearts on Fire people never claimed H&A status even though they focus on great symetry (and have a wonderfull scope). They also had the best H&A patterns I have seen - in every diamond I looked at (about 1/2 dozen of them). Absolutely buetiful diamonds... Anyone want to give me an extra 4 or 5 thousand so I can afford to purchase one.

What was really interesting was that they had 1/4 carat Hearts on Fire diamonds. Most premium cut diamond brands do not cut anything less than 1/2 carat diamonds. (this was a week after I got my matched pair of 1/4 carat diamonds. I should have taken them along for a comparison in their store lighing and under their symetry scope).

Perry

Perry

 

[Dancing Fire]

Date: 1/22/2005 10:41:44 PM
Author: perry
John:

All of those jewelry stores I visit that are selling ''H&A'' diamonds and love showing off their H&A patterns.... Are you implying that those arn''t ''true'' H&A. Those jewelers think so....

What was really interesting was that the Hearts on Fire people never claimed H&A status even though they focus on great symetry (and have a wonderfull scope). They also had the best H&A patterns I have seen - in every diamond I looked at (about 1/2 dozen of them). Absolutely buetiful diamonds... Anyone want to give me an extra 4 or 5 thousand so I can afford to purchase one.

What was really interesting was that they had 1/4 carat Hearts on Fire diamonds. Most premium cut diamond brands do not cut anything less than 1/2 carat diamonds. (this was a week after I got my matched pair of 1/4 carat diamonds. I should have taken them along for a comparison in their store lighing and under their symetry scope).

Perry

Perry

Perry
HOF may not claim(depending on which vendor) h&a status ,but they sure claim their HOF diamonds are the worlds most perfectly cut diamonds.

 

[strmrdr]

off topic: perry you write very well you should consider doing an article.

On topic:
My opinion:
It looks like a top line h&a diamond to me.

 

[perry]

Strmrdr:

Thanks for the complement. I''ve allways done well in technical writing compared to many other engneers (for those of you who have not figured that out

) - even if my grammer and spelling need help (and I have wore out more dictionairies than most people ever owned: equations stick, words don''t - and grammer structure escapes me entirely).

I agree that the HOF diamonds look like a top line H&A diamond line.

Dancing Fire:

You are right about HOF claiming to be the world best cut diamonds. One of the first things out of the jewelry store''s owners mouth... I promptly replied that 8* would dispute that. He mumbled a bit, but conceeded that at least the question could be discussed between the two lines. I am actually hoping to look at 8* next month on a trip to Chicago.

Have a nice day folks, I will be on a delayed trip most of the day (The alley did not get plowed until late yesturday and there was too much snow for my car to handle).

Perry

 

[Rhino]

Very nice stone. One correction ... that is not a LightScope image. LightScope images show more detail than that.

Peace,